diff --git a/README.md b/README.md
index 437116a..acb2920 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ Testing is done with mocha and can be executed using `npm test`.
 
 ## General structure
 
-[index.ts](./src/index.ts) is exectued when starting the server. It includes all setup tasks, registers middleware,
+[index.ts](./src/index.ts) is executed when starting the server. It includes all setup tasks, registers middleware,
 routes and error handlers. Setting the `NODE_ENV` environment variable allows starting the server either in 
 `production`, `development` or `test` mode.
 
diff --git a/api/api.yaml b/api/api.yaml
index d85acc7..5d0ab02 100644
--- a/api/api.yaml
+++ b/api/api.yaml
@@ -65,6 +65,7 @@ tags:
   - name: /template
   - name: /model
   - name: /user
+  - name: /help
 
 
 paths:
@@ -76,6 +77,7 @@ paths:
     - $ref: 'template.yaml'
     - $ref: 'model.yaml'
     - $ref: 'user.yaml'
+    - $ref: 'help.yaml'
 
 
 components:
diff --git a/api/help.yaml b/api/help.yaml
new file mode 100644
index 0000000..de36cbe
--- /dev/null
+++ b/api/help.yaml
@@ -0,0 +1,60 @@
+/help/{key}:
+  parameters:
+    - $ref: 'api.yaml#/components/parameters/Key'
+  get:
+    summary: get help text for key
+    description: 'Auth: basic, levels: predict, read, write, dev, admin, depending on the set document level'
+    tags:
+      - /help
+    responses:
+      200:
+        description: the required text
+        content:
+          application/json:
+            schema:
+              $ref: 'api.yaml#/components/schemas/Help'
+      403:
+        $ref: 'api.yaml#/components/responses/403'
+      404:
+        $ref: 'api.yaml#/components/responses/404'
+      500:
+        $ref: 'api.yaml#/components/responses/500'
+  post:
+    summary: add/replace help text
+    description: 'Auth: basic, levels: dev, admin <br> If the given key exists, the item is replaced,
+      otherwise it is newly created'
+    tags:
+      - /help
+    requestBody:
+      required: true
+      content:
+        application/json:
+          schema:
+            $ref: 'api.yaml#/components/schemas/Help'
+    responses:
+      200:
+        $ref: 'api.yaml#/components/responses/Ok'
+      400:
+        $ref: 'api.yaml#/components/responses/400'
+      401:
+        $ref: 'api.yaml#/components/responses/401'
+      403:
+        $ref: 'api.yaml#/components/responses/403'
+      500:
+        $ref: 'api.yaml#/components/responses/500'
+  delete:
+    summary: remove help text
+    description: 'Auth: basic, levels: dev, admin'
+    tags:
+      - /help
+    responses:
+      200:
+        $ref: 'api.yaml#/components/responses/Ok'
+      401:
+        $ref: 'api.yaml#/components/responses/401'
+      403:
+        $ref: 'api.yaml#/components/responses/403'
+      404:
+        $ref: 'api.yaml#/components/responses/404'
+      500:
+        $ref: 'api.yaml#/components/responses/500'
\ No newline at end of file
diff --git a/api/parameters.yaml b/api/parameters.yaml
index 192b15a..a17127f 100644
--- a/api/parameters.yaml
+++ b/api/parameters.yaml
@@ -46,4 +46,13 @@ Group:
   required: true
   schema:
     type: string
-  example: vn
\ No newline at end of file
+  example: vn
+
+Key:
+  name: key
+  description: URIComponent encoded string
+  in: path
+  required: true
+  schema:
+    type: string
+  example: '%2Fdocumentation%2Fdatabase'
\ No newline at end of file
diff --git a/api/sample.yaml b/api/sample.yaml
index 1359d23..6816022 100644
--- a/api/sample.yaml
+++ b/api/sample.yaml
@@ -52,7 +52,8 @@
       - name: filters[]
         description: "the filters to apply as an array of URIComponent encoded objects in the form {mode:
         'eq/ne/lt/lte/gt/gte/in/nin/stringin', field: 'material.m', values: ['15']} using
-        encodeURIComponent(JSON.stringify({}))"
+        encodeURIComponent(JSON.stringify({})) <br>Use {mode: 'eq', field: 'condition', values: [{}]} and
+        {mode: 'eq', field: 'measurements', values: [null]} to filter for samples without condition or measurements"
         in: query
         schema:
          type: array
diff --git a/api/schemas.yaml b/api/schemas.yaml
index a61a819..1da048f 100644
--- a/api/schemas.yaml
+++ b/api/schemas.yaml
@@ -232,4 +232,14 @@ ModelItem:
       example: https://definma-model-test.apps.de1.bosch-iot-cloud.com/predict/model1-1
     label:
       type: string
-      example: 'ml/g'
\ No newline at end of file
+      example: 'ml/g'
+
+Help:
+  properties:
+    text:
+      type: string
+      example: This page documents the database.
+    level:
+      type: string
+      description: can be also null to allow access without authorization
+      example: read
\ No newline at end of file
diff --git a/src/db.ts b/src/db.ts
index 2e8592d..b82151d 100644
--- a/src/db.ts
+++ b/src/db.ts
@@ -85,7 +85,7 @@ export default class db {
       cron.schedule('0 0 * * *', () => {
         ChangelogModel.deleteMany({_id: {$lt:  // id from time
           Math.floor(new Date().getTime() / 1000 - changelogKeepDays * 24 * 60 * 60).toString(16) + '0000000000000000'
-        }}).log({method: 'scheduled changelog delete', url: '', authDetails: {}}).lean().exec(err => {
+        }}).lean().exec(err => {
           if (err) console.error(err);
         });
       });
@@ -149,7 +149,6 @@ export default class db {
   // changelog entry, expects (req, this (from query helper)) or (req, collection, conditions, data)
   static log(req, thisOrCollection, conditions = null, data = null) {
     if (! (conditions || data)) {  // (req, this)
-      console.log(11);
       data = thisOrCollection._update ? _.cloneDeep(thisOrCollection._update) : {};  // replace undefined with {}
       // replace keys with a leading $
       Object.keys(data).forEach(key => {
@@ -158,7 +157,6 @@ export default class db {
           delete data[key];
         }
       });
-      console.log(thisOrCollection._conditions);
       new ChangelogModel(this.logEscape(_.cloneDeep({
         action: req.method + ' ' + req.url,
         collection_name: thisOrCollection._collection.collectionName,
diff --git a/src/helpers/csv.ts b/src/helpers/csv.ts
index d7774d7..5e8ae03 100644
--- a/src/helpers/csv.ts
+++ b/src/helpers/csv.ts
@@ -1,7 +1,7 @@
 import {parseAsync} from 'json2csv';
 import flatten from './flatten';
 
-export default function csv(input: any[], f: (err, data) => void) {
+export default function csv(input: any[], f: (err, data) => void) {  // parse JSON to CSV
   parseAsync(input.map(e => flatten(e)), {includeEmptyRows: true})
     .then(csv => f(null, csv))
     .catch(err => f(err, null));
diff --git a/src/helpers/flatten.ts b/src/helpers/flatten.ts
index ed54da9..d28bd64 100644
--- a/src/helpers/flatten.ts
+++ b/src/helpers/flatten.ts
@@ -3,10 +3,10 @@ import globals from '../globals';
 export default function flatten (data, keepArray = false) {  // flatten object: {a: {b: true}} -> {a.b: true}
   const result = {};
   function recurse (cur, prop) {
-    if (Object(cur) !== cur || Object.keys(cur).length === 0) {
+    if (Object(cur) !== cur || Object.keys(cur).length === 0) {  // simple value
       result[prop] = cur;
     }
-    else if (prop === `${globals.spectrum.spectrum}.${globals.spectrum.dpt}`) {
+    else if (prop === `${globals.spectrum.spectrum}.${globals.spectrum.dpt}`) {  // convert spectrum for ML
       result[prop + '.labels'] = cur.map(e => parseFloat(e[0]));
       result[prop + '.values'] = cur.map(e => parseFloat(e[1]));
     }
@@ -27,7 +27,7 @@ export default function flatten (data, keepArray = false) {  // flatten object:
         }
       }
     }
-    else {
+    else {  // object
       let isEmpty = true;
       for (let p in cur) {
         isEmpty = false;
diff --git a/src/helpers/mail.ts b/src/helpers/mail.ts
index a76b287..2c0ab57 100644
--- a/src/helpers/mail.ts
+++ b/src/helpers/mail.ts
@@ -4,10 +4,10 @@ import axios from 'axios';
 
 export default class Mail{
 
-  static readonly address = 'definma@bosch-iot.com';
-  static uri: string;
-  static auth = {username: '', password: ''};
-  static mailPass: string;
+  static readonly address = 'definma@bosch-iot.com';  // email address
+  static uri: string;                                 // mail API URI
+  static auth = {username: '', password: ''};         // mail API credentials
+  static mailPass: string;                            // mail API generates password
 
   static init() {
     if (process.env.NODE_ENV === 'production') {  // only send mails in production
@@ -51,14 +51,14 @@ export default class Mail{
       }).then(() => {  // init done successfully
         console.info('Mail service established successfully');
         this.send('lukas.veit@bosch.com', 'Mail Service started', new Date().toString());
-      }).catch(err => {  // anywhere an error occurred
+      }).catch(err => {  // somewhere an error occurred
         console.error(`Mail init error: ${err.request.method} ${err.request.path}: ${err.response.status}`,
           err.response.data);
       });
     }
   }
 
-  static send (mailAddress, subject, content, f: (x?) => void = () => {}) {  // callback, executed empty or with error
+  static send (mailAddress, subject, content, f: (x?) => void = () => {}) {  // callback executed empty or with error
     if (process.env.NODE_ENV === 'production') {  // only send mails in production
       axios({
         method: 'post',
diff --git a/src/index.ts b/src/index.ts
index a1c7417..f64e847 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -100,6 +100,9 @@ app.use(require('./helpers/authorize'));  // handle authentication
 // redirect /api routes for Angular proxy in development
 if (process.env.NODE_ENV !== 'production') {
   app.use('/api/:url([^]+)', (req, res) => {
+    if (/help\//.test(req.params.url)) { // encode URI again for help route
+      req.params.url = 'help/' + encodeURIComponent(req.params.url.replace('help/', ''));
+    }
     req.url = '/' + req.params.url;
     app.handle(req, res);
   });
@@ -114,6 +117,7 @@ app.use('/', require('./routes/measurement'));
 app.use('/', require('./routes/template'));
 app.use('/', require('./routes/model'));
 app.use('/', require('./routes/user'));
+app.use('/', require('./routes/help'));
 
 // static files
 app.use('/static', express.static('static'));
diff --git a/src/models/help.ts b/src/models/help.ts
new file mode 100644
index 0000000..a04ae33
--- /dev/null
+++ b/src/models/help.ts
@@ -0,0 +1,16 @@
+import db from '../db';
+import mongoose from 'mongoose';
+
+const HelpSchema = new mongoose.Schema({
+  key: {type: String, index: {unique: true}},
+  level: String,
+  text: String
+}, {minimize: false});
+
+// changelog query helper
+HelpSchema.query.log = function <Q extends mongoose.DocumentQuery<any, any>> (req) {
+  db.log(req, this);
+  return this;
+}
+
+export default mongoose.model<any, mongoose.Model<any, any>>('help', HelpSchema);
\ No newline at end of file
diff --git a/src/routes/help.spec.ts b/src/routes/help.spec.ts
new file mode 100644
index 0000000..590d47b
--- /dev/null
+++ b/src/routes/help.spec.ts
@@ -0,0 +1,184 @@
+import should from 'should/as-function';
+import TestHelper from "../test/helper";
+import HelpModel from '../models/help';
+
+
+describe('/help', () => {
+  let server;
+  before(done => TestHelper.before(done));
+  beforeEach(done => server = TestHelper.beforeEach(server, done));
+  afterEach(done => TestHelper.afterEach(server, done));
+  after(done => TestHelper.after(done));
+
+  describe('GET /help/{key}', () => {
+    it('returns the required text', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/help/%2Fsamples',
+        auth: {basic: 'janedoe'},
+        httpStatus: 200,
+        res: {text: 'Samples help', level: 'read'}
+      });
+    });
+    it('returns the required text without authorization if allowed', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/help/%2Fdocumentation',
+        auth: {basic: 'janedoe'},
+        httpStatus: 200,
+        res: {text: 'Documentation help', level: 'none'}
+      });
+    });
+    it('returns 404 for an invalid key', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/help/documentation/database',
+        httpStatus: 404
+      });
+    });
+    it('returns 404 for an unknown key', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/help/xxx',
+        auth: {basic: 'janedoe'},
+        httpStatus: 404
+      });
+    });
+    it('returns 403 for a text with a higher level than given', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/help/%2Fmodels',
+        auth: {basic: 'janedoe'},
+        httpStatus: 403
+      });
+    });
+    it('rejects an API key', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/help/%2Fsamples',
+        auth: {api: 'janedoe'},
+        httpStatus: 401,
+      });
+    });
+    it('rejects an unauthorized request if a level is given', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/help/%2Fsamples',
+        httpStatus: 401
+      });
+    });
+  });
+
+  describe('POST /help/{key}', () => {
+    it('changes the required text', done => {
+      TestHelper.request(server, done, {
+        method: 'post',
+        url: '/help/%2Fsamples',
+        auth: {basic: 'admin'},
+        httpStatus: 200,
+        req: {text: 'New samples help', level: 'write'}
+      }).end((err, res) => {
+        if (err) return done(err);
+        should(res.body).be.eql({status: 'OK'});
+        HelpModel.find({key: '/samples'}).lean().exec((err, data) => {
+          if (err) return done(err);
+          should(data).have.lengthOf(1);
+          should(data[0]).have.only.keys('_id', 'key', 'text', 'level');
+          should(data[0]).property('key', '/samples');
+          should(data[0]).property('text', 'New samples help');
+          should(data[0]).property('level', 'write');
+          done();
+        });
+      });
+    });
+    it('saves a new text', done => {
+      TestHelper.request(server, done, {
+        method: 'post',
+        url: '/help/%2Fmaterials',
+        auth: {basic: 'admin'},
+        httpStatus: 200,
+        req: {text: 'Materials help', level: 'dev'}
+      }).end((err, res) => {
+        if (err) return done(err);
+        should(res.body).be.eql({status: 'OK'});
+        HelpModel.find({key: '/materials'}).lean().exec((err, data) => {
+          if (err) return done(err);
+          should(data).have.lengthOf(1);
+          should(data[0]).have.only.keys('_id', 'key', 'text', 'level', '__v');
+          should(data[0]).property('key', '/materials');
+          should(data[0]).property('text', 'Materials help');
+          should(data[0]).property('level', 'dev');
+          done();
+        });
+      });
+    });
+    it('rejects an API key', done => {
+      TestHelper.request(server, done, {
+        method: 'post',
+        url: '/help/%2Fsamples',
+        auth: {key: 'admin'},
+        httpStatus: 401,
+        req: {text: 'New samples help', level: 'write'}
+      });
+    });
+    it('rejects a write user', done => {
+      TestHelper.request(server, done, {
+        method: 'post',
+        url: '/help/%2Fsamples',
+        auth: {basic: 'janedoe'},
+        httpStatus: 403,
+        req: {text: 'New samples help', level: 'write'}
+      });
+    });
+    it('rejects an unauthorized request', done => {
+      TestHelper.request(server, done, {
+        method: 'post',
+        url: '/help/%2Fsamples',
+        httpStatus: 401,
+        req: {text: 'New samples help', level: 'write'}
+      });
+    });
+  });
+
+  describe('DELETE /help/{key}', () => {
+    it('deletes the required entry', done => {
+      TestHelper.request(server, done, {
+        method: 'delete',
+        url: '/help/%2Fsamples',
+        auth: {basic: 'admin'},
+        httpStatus: 200
+      }).end((err, res) => {
+        if (err) return done(err);
+        should(res.body).be.eql({status: 'OK'});
+        HelpModel.find({key: '/materials'}).lean().exec((err, data) => {
+          if (err) return done(err);
+          should(data).have.lengthOf(0);
+          done();
+        });
+      });
+    });
+    it('rejects an API key', done => {
+      TestHelper.request(server, done, {
+        method: 'delete',
+        url: '/help/%2Fsamples',
+        auth: {key: 'admin'},
+        httpStatus: 401
+      });
+    });
+    it('rejects a write user', done => {
+      TestHelper.request(server, done, {
+        method: 'delete',
+        url: '/help/%2Fsamples',
+        auth: {basic: 'janedoe'},
+        httpStatus: 403
+      });
+    });
+    it('rejects an unauthorized request', done => {
+      TestHelper.request(server, done, {
+        method: 'delete',
+        url: '/help/%2Fsamples',
+        httpStatus: 401
+      });
+    });
+  });
+});
\ No newline at end of file
diff --git a/src/routes/help.ts b/src/routes/help.ts
new file mode 100644
index 0000000..3a2cb51
--- /dev/null
+++ b/src/routes/help.ts
@@ -0,0 +1,55 @@
+import express from 'express';
+import HelpModel from '../models/help';
+import HelpValidate from './validate/help';
+import res400 from './validate/res400';
+import globals from '../globals';
+
+const router = express.Router();
+
+router.get('/help/:key', (req, res, next) => {
+  const {error: paramError, value: key} = HelpValidate.params(req.params);
+  if (paramError) return res400(paramError, res);
+
+  HelpModel.findOne(key).lean().exec((err, data) => {
+    if (err) return next(err);
+
+    if (!data) {
+      return res.status(404).json({status: 'Not found'});
+    }
+    if (data.level !== 'none') {  // check level
+      if (!req.auth(res,
+        Object.values(globals.levels).slice(Object.values(globals.levels).findIndex(e => e === data.level))
+        , 'basic')) return;
+    }
+    res.json(HelpValidate.output(data));
+  })
+});
+
+router.post('/help/:key', (req, res, next) => {
+  if (!req.auth(res, ['dev', 'admin'], 'basic')) return;
+  const {error: paramError, value: key} = HelpValidate.params(req.params);
+  if (paramError) return res400(paramError, res);
+  const {error, value: help} = HelpValidate.input(req.body);
+  if (error) return res400(error, res);
+
+  HelpModel.findOneAndUpdate(key, help, {upsert: true}).log(req).lean().exec(err => {
+    if (err) return next(err);
+    res.json({status: 'OK'});
+  });
+});
+
+router.delete('/help/:key', (req, res, next) => {
+  if (!req.auth(res, ['dev', 'admin'], 'basic')) return;
+  const {error: paramError, value: key} = HelpValidate.params(req.params);
+  if (paramError) return res400(paramError, res);
+
+  HelpModel.findOneAndDelete(key).log(req).lean().exec((err, data) => {
+    if (err) return next(err);
+    if (!data) {
+      return res.status(404).json({status: 'Not found'});
+    }
+    res.json({status: 'OK'});
+  });
+});
+
+module.exports = router;
\ No newline at end of file
diff --git a/src/routes/material.ts b/src/routes/material.ts
index a75f73d..3996e30 100644
--- a/src/routes/material.ts
+++ b/src/routes/material.ts
@@ -25,21 +25,7 @@ router.get('/materials', (req, res, next) => {
     MaterialValidate.query(req.query, ['dev', 'admin'].indexOf(req.authDetails.level) >= 0);
   if (error) return res400(error, res);
 
-  let conditions;
-
-  if (filters.hasOwnProperty('status')) {
-    if(filters.status === 'all') {
-      conditions = {$or: [{status: globals.status.val}, {status: globals.status.new}]}
-    }
-    else {
-      conditions = {status: filters.status};
-    }
-  }
-  else {  // default
-    conditions = {status: globals.status.val};
-  }
-
-  MaterialModel.find(conditions).sort({name: 1}).populate('group_id').populate('supplier_id')
+  MaterialModel.find(filters).sort({name: 1}).populate('group_id').populate('supplier_id')
     .lean().exec((err, data) => {
     if (err) return next(err);
 
diff --git a/src/routes/sample.spec.ts b/src/routes/sample.spec.ts
index 16107c9..9a53e29 100644
--- a/src/routes/sample.spec.ts
+++ b/src/routes/sample.spec.ts
@@ -440,6 +440,48 @@ describe('/sample', () => {
         done();
       });
     });
+    it('filters for empty conditions', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/samples?status[]=new&status[]=validated&fields[]=number&fields[]=condition&filters[]=%7B%22mode%22%3A%22eq%22%2C%22field%22%3A%22condition%22%2C%22values%22%3A%5B%7B%7D%5D%7D',
+        auth: {basic: 'janedoe'},
+        httpStatus: 200
+      }).end((err, res) => {
+        if (err) return done(err);
+        const json = require('../test/db.json');
+        should(res.body).have.lengthOf(
+          json.collections.samples
+            .filter(e => e.status !== 'deleted')
+            .filter(e => Object.keys(e.condition).length === 0)
+            .length
+        );
+        should(res.body).matchEach(sample => {
+          should(sample.condition).be.eql({});
+        });
+        done();
+      });
+    });
+    it('filters for samples without measurements', done => {
+      TestHelper.request(server, done, {
+        method: 'get',
+        url: '/samples?status[]=new&status[]=validated&fields[]=number&fields[]=_id&filters[]=%7B%22mode%22%3A%22eq%22%2C%22field%22%3A%22measurements%22%2C%22values%22%3A%5Bnull%5D%7D',
+        auth: {basic: 'janedoe'},
+        httpStatus: 200
+      }).end((err, res) => {
+        if (err) return done(err);
+        const json = require('../test/db.json');
+        should(res.body).have.lengthOf(
+          json.collections.samples
+            .filter(e => e.status !== 'deleted')
+            .filter(e => !json.collections.measurements.find(el => el.sample_id.toString() === e._id.toString()))
+            .length
+        );
+        should(res.body).matchEach(sample => {
+          should(json.collections.measurements.find(el => el.sample_id.toString() === sample._id)).be.eql(undefined);
+        });
+        done();
+      });
+    });
     it('returns comment fields', done => {
       TestHelper.request(server, done, {
         method: 'get',
diff --git a/src/routes/sample.ts b/src/routes/sample.ts
index 4726bd3..71e84e9 100644
--- a/src/routes/sample.ts
+++ b/src/routes/sample.ts
@@ -22,16 +22,12 @@ import globals from '../globals';
 
 const router = express.Router();
 
-// TODO: do not use streaming for spectrum filenames
-
 
 router.get('/samples', async (req, res, next) => {
   if (!req.auth(res, ['read', 'write', 'dev', 'admin'], 'all')) return;
 
   const {error, value: filters} = SampleValidate.query(req.query, ['dev', 'admin'].indexOf(req.authDetails.level) >= 0);
-  console.log(error);
   if (error) return res400(error, res);
-  console.log(filters.filters);
 
   // spectral data and csv not allowed for read/write users
   if ((filters.fields.find(e => e.indexOf('.' + globals.spectrum.dpt) >= 0) || filters.output !== 'json') &&
@@ -219,6 +215,15 @@ router.get('/samples', async (req, res, next) => {
     }
   }
 
+  if (sortFilterKeys.find(e => e === 'measurements')) {  // filter for samples without measurements
+    queryPtr.push({$lookup: {
+        from: 'measurements', let: {sId: '$_id'},
+        pipeline: [{$match:{$expr:{$and:[{$eq:['$sample_id','$$sId']}]}}}, {$project: {_id: true}}],
+        as: 'measurementCount'
+      }},
+      {$match: {measurementCount: {$size: 0}}}
+    );
+  }
   const measurementFilterFields = _.uniq(sortFilterKeys.filter(e => /measurements\./.test(e))
     .map(e => e.split('.')[1]));  // filter measurement names and remove duplicates from parameters
   if (sortFilterKeys.find(e => /measurements\./.test(e))) {  //  add measurement fields
@@ -235,7 +240,7 @@ router.get('/samples', async (req, res, next) => {
     ];
     if (measurementFilterFields.indexOf(globals.spectrum.spectrum) >= 0) {  // filter out dpts
       pipeline.push(
-        {$project: {'values.device': true, measurement_template: true}},
+        {$project: {['values.' + globals.spectrum.dpt]: false}},
         {$addFields: {'values._id': '$_id'}}
       );
     }
@@ -379,7 +384,6 @@ router.get('/samples', async (req, res, next) => {
     projection._id = false;
   }
   queryPtr.push({$project: projection});
-  console.log(JSON.stringify(query));
   // use streaming when including spectrum files
   if (!fieldsToAdd.find(e => e.indexOf(globals.spectrum.spectrum + '.' + globals.spectrum.dpt) >= 0)) {
     collection.aggregate(query).allowDiskUse(true).exec((err, data) => {
@@ -678,11 +682,10 @@ async function numberGenerate (sample, req, res, next) {
   const sampleData = await SampleModel
     .aggregate([
       {$match: {number: new RegExp('^' + req.authDetails.location + '[0-9]+$', 'm')}},
-      // {$addFields: {number2: {$toDecimal: {$arrayElemAt: [{$split: [{$arrayElemAt:
-      //   [{$split: ['$number', 'Rng']}, 1]}, '_']}, 0]}}}},  // not working with MongoDb 3.6
       {$addFields: {sortNumber: {$let: {
         vars: {tmp: {$concat: ['000000000000000000000000000000',
-              {$arrayElemAt: [{$split: [{$arrayElemAt: [{$split: ['$number', 'Rng']}, 1]}, '_']}, 0]}]}},
+              {$arrayElemAt: [{$split:
+                    [{$arrayElemAt: [{$split: ['$number', req.authDetails.location]}, 1]}, '_']}, 0]}]}},
         in: {$substrCP: ['$$tmp', {$subtract: [{$strLenCP: '$$tmp'}, 30]}, {$strLenCP: '$$tmp'}]}
       }}}},
       {$sort: {sortNumber: -1}},
diff --git a/src/routes/template.spec.ts b/src/routes/template.spec.ts
index 16da61d..d7e4b79 100644
--- a/src/routes/template.spec.ts
+++ b/src/routes/template.spec.ts
@@ -1,7 +1,11 @@
 import should from 'should/as-function';
 import _ from 'lodash';
 import TemplateConditionModel from '../models/condition_template';
+import SampleModel from '../models/sample';
+import MeasurementModel from '../models/measurement';
+import MaterialModel from '../models/material';
 import TestHelper from "../test/helper";
+import mongoose from 'mongoose';
 
 
 describe('/template', () => {
@@ -90,7 +94,7 @@ describe('/template', () => {
       });
     });
 
-    describe('PUT /template/condition/{name}', () => {
+    describe('PUT /template/condition/{id}', () => {
       it('returns the right condition template', done => {
         TestHelper.request(server, done, {
           method: 'put',
@@ -145,6 +149,24 @@ describe('/template', () => {
             });
           });
       });
+      it('renames all occurrences instead of creating a new version when only the parameter name is changed', done => {
+        TestHelper.request(server, done, {
+          method: 'put',
+          url: '/template/condition/200000000000000000000001',
+          auth: {basic: 'admin'},
+          httpStatus: 200, req: {name: 'heat treatment', parameters: [{name: 'treatmentMaterial', range: {values: ['copper', 'hot air']}}, {name: 'weeks', range: {min: 1, max: 10, required: true}}]}
+        }).end((err, res) => {
+          if (err) return done(err);
+          should(res.body).be.eql({_id: '200000000000000000000001', name: 'heat treatment', version: 1, first_id: '200000000000000000000001', parameters: [{name: 'treatmentMaterial', range: {values: ['copper', 'hot air']}}, {name: 'weeks', range: {min: 1, max: 10, required: true}}]});
+          SampleModel.find({'condition.condition_template': mongoose.Types.ObjectId('200000000000000000000001')}).lean().exec((err, data:any) => {
+            if (err) return done(err);
+            should(data).matchEach(sample => {
+              should(sample.condition).have.only.keys('treatmentMaterial', 'weeks', 'condition_template');
+            });
+            done();
+          });
+        });
+      });
       it('creates a changelog', done => {
         TestHelper.request(server, done, {
           method: 'put',
@@ -161,7 +183,7 @@ describe('/template', () => {
           }
         });
       });
-      it('allows changing only one property', done => {
+      it('does not increase the version on name change', done => {
         TestHelper.request(server, done, {
           method: 'put',
           url: '/template/condition/200000000000000000000001',
@@ -175,7 +197,7 @@ describe('/template', () => {
             should(data).have.only.keys('_id', 'first_id', 'name', 'version', 'parameters', '__v');
             should(data.first_id.toString()).be.eql('200000000000000000000001');
             should(data).have.property('name', 'heat aging');
-            should(data).have.property('version', 2);
+            should(data).have.property('version', 1);
             should(data).have.property('parameters').have.lengthOf(2);
             should(data.parameters[0]).have.property('name', 'material');
             should(data.parameters[1]).have.property('name', 'weeks');
@@ -183,6 +205,28 @@ describe('/template', () => {
           });
         });
       });
+      it('does not increase the version on name change when property ranges stayed the same', done => {
+        TestHelper.request(server, done, {
+          method: 'put',
+          url: '/template/condition/200000000000000000000001',
+          auth: {basic: 'admin'},
+          httpStatus: 200,
+          req: {name: 'heat aging', parameters: [{name: 'material', range: {values: ['copper', 'hot air']}}, {name: 'duration', range: {min: 1, max: 10, required: true}}]}
+        }).end((err, res) => {
+          if (err) return done(err);
+          TemplateConditionModel.findById(res.body._id).lean().exec((err, data:any) => {
+            if (err) return done(err);
+            should(data).have.only.keys('_id', 'first_id', 'name', 'version', 'parameters', '__v');
+            should(data.first_id.toString()).be.eql('200000000000000000000001');
+            should(data).have.property('name', 'heat aging');
+            should(data).have.property('version', 1);
+            should(data).have.property('parameters').have.lengthOf(2);
+            should(data.parameters[0]).have.property('name', 'material');
+            should(data.parameters[1]).have.property('name', 'duration');
+            done();
+          });
+        });
+      });
       it('supports values ranges', done => {
         TestHelper.request(server, done, {
           method: 'put',
@@ -526,6 +570,26 @@ describe('/template', () => {
         });
       });
     });
+    describe('PUT /template/measurement/{id}', () => {
+      it('renames all occurrences instead of creating a new version when only the parameter name is changed', done => {
+        TestHelper.request(server, done, {
+          method: 'put',
+          url: '/template/measurement/300000000000000000000001',
+          auth: {basic: 'admin'},
+          httpStatus: 200, req: {name: 'spectrum', parameters: [{name: 'spectrumValues', range: {type: 'array'}}, {name: 'device', range: {}}, {name: 'filename', range: {}}]}
+        }).end((err, res) => {
+          if (err) return done(err);
+          should(res.body).be.eql({_id: '300000000000000000000001', name: 'spectrum', version: 1, first_id: '300000000000000000000001', parameters: [{name: 'spectrumValues', range: {type: 'array'}}, {name: 'device', range: {}}, {name: 'filename', range: {}}]});
+          MeasurementModel.find({'measurement_template': mongoose.Types.ObjectId('300000000000000000000001')}).lean().exec((err, data:any) => {
+            if (err) return done(err);
+            should(data).matchEach(measurement => {
+              should(measurement.values).have.only.keys('spectrumValues', 'device', 'filename');
+            });
+            done();
+          });
+        });
+      });
+    });
     // other methods should be covered by condition tests
   });
 
@@ -571,6 +635,27 @@ describe('/template', () => {
         });
       });
     });
+    describe('PUT /template/material/{id}', () => {
+      it('renames all occurrences instead of creating a new version when only the parameter name is changed', done => {
+        TestHelper.request(server, done, {
+          method: 'put',
+          url: '/template/material/130000000000000000000003',
+          auth: {basic: 'admin'},
+          httpStatus: 200,
+          req: {name: 'plastic', parameters: [ {name: 'glassfiber', range: {min: 0, max: 100, required: true}}, {name: 'carbonfiber', range: {min: 0, max: 100, required: true}}, {name: 'mineral', range: {min: 0, max: 100, required: true}}]}
+        }).end((err, res) => {
+          if (err) return done(err);
+          should(res.body).be.eql({_id: '130000000000000000000003', name: 'plastic', version: 2, first_id: '130000000000000000000001', parameters: [ {name: 'glassfiber', range: {min: 0, max: 100, required: true}}, {name: 'carbonfiber', range: {min: 0, max: 100, required: true}}, {name: 'mineral', range: {min: 0, max: 100, required: true}}]});
+          MaterialModel.find({'properties': mongoose.Types.ObjectId('130000000000000000000003')}).lean().exec((err, data:any) => {
+            if (err) return done(err);
+            should(data).matchEach(material => {
+              should(material.parameters).have.only.keys('glassfiber', 'carbonfiber', 'mineral', 'material_template');
+            });
+            done();
+          });
+        });
+      });
+    });
     // other methods should be covered by condition tests
   });
 });
\ No newline at end of file
diff --git a/src/routes/template.ts b/src/routes/template.ts
index ad73a8c..8eeffdd 100644
--- a/src/routes/template.ts
+++ b/src/routes/template.ts
@@ -5,6 +5,9 @@ import TemplateValidate from './validate/template';
 import ConditionTemplateModel from '../models/condition_template';
 import MeasurementTemplateModel from '../models/measurement_template';
 import MaterialTemplateModel from '../models/material_template';
+import SampleModel from '../models/sample';
+import MaterialModel from '../models/material';
+import MeasurementModel from '../models/measurement';
 import res400 from './validate/res400';
 import IdValidate from './validate/id';
 import mongoose from "mongoose";
@@ -61,13 +64,66 @@ router.put('/template/:collection(measurement|condition|material)/' + IdValidate
   }
 
   if (!_.isEqual(_.pick(templateData, _.keys(template)), template)) {  // data was changed
-    template.version = templateData.version + 1;  // increase version
-    // save new template, fill with old properties
-    await new (model(req))(_.assign({}, _.omit(templateData, ['_id', '__v']), template)).save((err, data) => {
-      if (err) next (err);
-      db.log(req, req.params.collection + '_templates', {_id: data._id}, data.toObject());
-      res.json(TemplateValidate.output(data.toObject()));
-    });
+    if (!template.parameters || _.isEqual(templateData.parameters, template.parameters)) {  // only name was changed
+      model(req).findByIdAndUpdate(req.params.id, {name: template.name}, {new: true})
+        .log(req).lean().exec((err, data) => {
+        if (err) next (err);
+        res.json(TemplateValidate.output(data));
+      });
+    }
+    else if (template.parameters.filter((e, i) => _.isEqual(e.range, templateData.parameters[i].range)).length
+      === templateData.parameters.length) {  // only names changed
+      const changedParameterNames = template.parameters.map((e, i) => (  // list of new names
+          {name: e.name, index: i, oldName: templateData.parameters[i].name}
+        )).filter(e => e.name !== e.oldName);
+
+      // custom mappings for different collections
+      let targetModel;  // model of the collection where the template is used
+      let pathPrefix;   // path to the parameters in use
+      let templatePath; // complete path of the template property
+      switch (req.params.collection) {
+        case 'condition':
+          targetModel = SampleModel;
+          pathPrefix = 'condition.';
+          templatePath = 'condition.condition_template';
+          break;
+        case 'measurement':
+          targetModel = MeasurementModel;
+          pathPrefix = 'values.';
+          templatePath = 'measurement_template';
+          break;
+        case 'material':
+          targetModel = MaterialModel;
+          pathPrefix = 'properties.';
+          templatePath = 'properties.material_template';
+          break;
+      }
+
+      targetModel.updateMany({[templatePath]: mongoose.Types.ObjectId(templateData._id)},
+        {$rename:
+          changedParameterNames.reduce((s, e) => {s[pathPrefix + e.oldName] = pathPrefix + e.name; return s;}, {})
+        }) .log(req).lean().exec(err => {
+        if (err) return next(err);
+        model(req).findByIdAndUpdate(req.params.id,
+          {$set:
+            changedParameterNames.reduce(
+              (s, e) => {s[`parameters.${e.index}.name`] = e.name; return s;}, {name: template.name}
+            ),
+          },{new: true}).log(req).lean().exec((err, data) => {
+          if (err) next (err);
+          res.json(TemplateValidate.output(data));
+        });
+      });
+    }
+    else {
+      template.version = templateData.version + 1;  // increase version
+      // save new template, fill with old properties
+      await new (model(req))(_.assign({}, _.omit(templateData, ['_id', '__v']), template)).save((err, data) => {
+        if (err) next (err);
+        db.log(req, req.params.collection + '_templates', {_id: data._id}, data.toObject());
+        res.json(TemplateValidate.output(data.toObject()));
+      });
+    }
   }
   else {
     res.json(TemplateValidate.output(templateData));
diff --git a/src/routes/validate/help.ts b/src/routes/validate/help.ts
new file mode 100644
index 0000000..6dcf64a
--- /dev/null
+++ b/src/routes/validate/help.ts
@@ -0,0 +1,34 @@
+import Joi from 'joi';
+import globals from '../../globals';
+
+export default class HelpValidate {
+  private static help = {
+    text: Joi.string()
+      .allow('')
+      .max(8192),
+
+    level: Joi.string()
+      .valid('none', ...Object.values(globals.levels))
+  }
+
+  static input (data) {
+    return Joi.object({
+      text: this.help.text.required(),
+      level: this.help.level.required()
+    }).validate(data);
+  }
+
+  static output (data) {
+    const {value, error} = Joi.object({
+      text: this.help.text,
+      level: this.help.level
+    }).validate(data, {stripUnknown: true});
+    return error !== undefined? null : value;
+  }
+
+  static params(data) {
+    return Joi.object({
+      key: Joi.string().min(1).max(128)
+    }).validate(data);
+  }
+}
\ No newline at end of file
diff --git a/src/routes/validate/sample.ts b/src/routes/validate/sample.ts
index 54f7bb4..efaedf1 100644
--- a/src/routes/validate/sample.ts
+++ b/src/routes/validate/sample.ts
@@ -98,6 +98,7 @@ export default class SampleValidate {
     'user_id',
     'material._id',
     'material.numbers',
+    'measurements',
     `measurements.${globals.spectrum.spectrum}.${globals.spectrum.dpt}`,
   ];
 
@@ -198,7 +199,6 @@ export default class SampleValidate {
             data.filters[i] = decodeURIComponent(data.filters[i]);
           }
           catch (ignore) {}
-          console.log(data.filters[i]);
           data.filters[i] = JSON.parse(data.filters[i]);
           data.filters[i].values = data.filters[i].values.map(e => {  // validate filter values
             if (e === null) {  // null values are always allowed
@@ -226,6 +226,12 @@ export default class SampleValidate {
               });
               field = 'value';
             }
+            else if (field === 'measurements') {
+              validator = Joi.object({
+                value: Joi.object({}).allow(null).disallow({})
+              });
+              field = 'value';
+            }
             else if (field === 'notes.comment') {
               field = 'comment';
               validator = this.sample.notes
diff --git a/src/routes/validate/user.ts b/src/routes/validate/user.ts
index 4ac78d4..c9288d7 100644
--- a/src/routes/validate/user.ts
+++ b/src/routes/validate/user.ts
@@ -75,7 +75,7 @@ export default class UserValidate {  // validate input for user
       }).validate(data);
     }
     else {
-      return{error: 'No parameter specified!', value: {}};
+      return {error: 'No parameter specified!', value: {}};
     }
   }
 
diff --git a/src/test/db.json b/src/test/db.json
index f6118d2..ea276da 100644
--- a/src/test/db.json
+++ b/src/test/db.json
@@ -893,6 +893,26 @@
         "user_id" : {"$oid": "000000000000000000000003"},
         "__v" : 0
       }
+    ],
+    "helps": [
+      {
+        "_id": {"$oid":"150000000000000000000001"},
+        "key": "/documentation",
+        "text": "Documentation help",
+        "level": "none"
+      },
+      {
+        "_id": {"$oid":"150000000000000000000002"},
+        "key": "/samples",
+        "text": "Samples help",
+        "level": "read"
+      },
+      {
+        "_id": {"$oid":"150000000000000000000003"},
+        "key": "/models",
+        "text": "Models help",
+        "level": "dev"
+      }
     ]
   }
 }
\ No newline at end of file