diff --git a/codemeta_generation.js b/codemeta_generation.js
index eb883bf..616e5eb 100644
--- a/codemeta_generation.js
+++ b/codemeta_generation.js
@@ -1,204 +1,204 @@
 /**
  * Copyright (C) 2019  The Software Heritage developers
  * See the AUTHORS file at the top-level directory of this distribution
  * License: GNU Affero General Public License version 3, or any later version
  * See top-level LICENSE file for more information
  */
 
 "use strict";
 
 const SPDX_PREFIX = 'https://spdx.org/licenses/';
 
 function emptyToUndefined(v) {
     if (v == null || v == "")
         return undefined;
     else
         return v;
 }
 
 function getIfSet(query) {
     return emptyToUndefined(document.querySelector(query).value);
 }
 
 function setIfDefined(query, value) {
     if (value !== undefined) {
         document.querySelector(query).value = value;
     }
 }
 
 // Names of codemeta properties with a matching HTML field name
 const directCodemetaFields = [
     'codeRepository',
     'contIntegration',
     'dateCreated',
     'datePublished',
     'dateModified',
     'issueTracker',
     'name',
     'version',
     'identifier',
     'description',
     'applicationCategory',
     'releaseNotes',
     'funding',
-    'runtimePlatform',
-    'operatingSystem',
     'developmentStatus',
-    'programmingLanguage',
     'isPartOf',
     'referencePublication'
     
 ];
 
 const splittedCodemetaFields = [
     ['keywords', ','],
+    ['programmingLanguage', ','],
+    ['runtimePlatform', ','],
+    ['operatingSystem', ','],
     ['softwareRequirements', '\n'],
     ['relatedLink', '\n'],
 ]
 
 // Names of codemeta properties with a matching HTML field name,
 // in a Person object
 const directPersonCodemetaFields = [
     'givenName',
     'familyName',
     'email',
     'affiliation'   
 ];
 
 function generatePerson(idPrefix) {
     var doc = {
         "@type": "Person",
         "@id": getIfSet(`#${idPrefix}_id`),
     }
     directPersonCodemetaFields.forEach(function (item, index) {
         doc[item] = getIfSet(`#${idPrefix}_${item}`);
     });
 
     return doc;
 }
 
 function generatePersons(prefix) {
     var persons = [];
     var nbPersons = getNbPersons(prefix);
 
     for (let personId = 1; personId <= nbPersons; personId++) {
         persons.push(generatePerson(`${prefix}_${personId}`));
     }
 
     return persons;
 }
 
 function generateCodemeta() {
     var inputForm = document.querySelector('#inputForm');
     var codemetaText, errorHTML;
 
     if (inputForm.checkValidity()) {
         var doc = {
             "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
             "@type": "SoftwareSourceCode",
             "license": SPDX_PREFIX + getIfSet('#license'),
         };
 
         // Generate most fields
         directCodemetaFields.forEach(function (item, index) {
             doc[item] = getIfSet('#' + item)
         });
 
         // Generate simple fields parsed simply by splitting
         splittedCodemetaFields.forEach(function (item, index) {
             const id = item[0];
             const separator = item[1];
             const value = getIfSet('#' + id);
             if (value !== undefined) {
-                doc[id] = value.split(separator);
+                doc[id] = value.split(separator).map(trimSpaces);
             }
         });
 
         // Generate dynamic fields
         doc = Object.assign(doc, {
             "author": generatePersons('author'),
             "contributor": generatePersons('contributor'),
         });
 
         codemetaText = JSON.stringify(doc, null, 4);
         errorHTML = "";
     }
     else {
         codemetaText = "";
         errorHTML = "invalid input (see error above)";
         inputForm.reportValidity();
     }
 
     document.querySelector('#codemetaText').innerText = codemetaText;
     setError(errorHTML);
 
     if (codemetaText) {
         // For restoring the form state on page reload
         sessionStorage.setItem('codemetaText', codemetaText);
     }
 }
 
 function importPersons(prefix, legend, docs) {
     if (docs === 'undefined') {
         return;
     }
 
     docs.forEach(function (doc, index) {
         var personId = addPerson(prefix, legend);
 
         setIfDefined(`#${personId}_id`, doc['@id']);
         directPersonCodemetaFields.forEach(function (item, index) {
             setIfDefined(`#${prefix}_${personId}_${item}`, doc[item]);
         });
     })
 }
 
 function importCodemeta() {
     var inputForm = document.querySelector('#inputForm');
     var codemetaText = document.querySelector('#codemetaText').innerText;
     var doc;
 
     try {
         doc = JSON.parse(codemetaText);
     }
     catch (e) {
         setError(`Could not read codemeta document because it is not valid JSON (${e})`);
         return;
     }
     resetForm();
 
     if (doc['license'] !== undefined && doc['license'].indexOf(SPDX_PREFIX) == 0) {
         var license = doc['license'].substring(SPDX_PREFIX.length);
         document.querySelector('#license').value = license;
     }
 
     directCodemetaFields.forEach(function (item, index) {
         setIfDefined('#' + item, doc[item]);
     });
 
     // Import simple fields by joining on their separator
     splittedCodemetaFields.forEach(function (item, index) {
         const id = item[0];
         const separator = item[1];
         let value = doc[id];
         if (value !== undefined) {
             if (Array.isArray(value)) {
                 value = value.join(separator);
             }
             setIfDefined('#' + id, value);
         }
     });
 
     importPersons('author', 'Author', doc['author'])
     importPersons('contributor', 'Contributor', doc['contributor'])
 
     setError("");
 }
 
 function loadStateFromStorage() {
     codemetaText = sessionStorage.getItem('codemetaText')
     if (codemetaText) {
         document.querySelector('#codemetaText').innerText = codemetaText;
         importCodemeta();
     }
 }
diff --git a/index.html b/index.html
index e4adcaf..4df5bf4 100644
--- a/index.html
+++ b/index.html
@@ -1,278 +1,278 @@
 <!doctype html>
 <!--
 Copyright (C) 2019  The Software Heritage developers
 See the AUTHORS file at the top-level directory of this distribution
 License: GNU Affero General Public License version 3, or any later version
 See top-level LICENSE file for more information
 -->
 <html lang="en">
 <head>
     <meta charset="utf-8">
     <title>CodeMeta generator</title>
     <script src="./utils.js"></script>
     <script src="./fields_data.js"></script>
     <script src="./dynamic_form.js"></script>
     <script src="./codemeta_generation.js"></script>
     <link rel="stylesheet" type="text/css" href="./style.css">
 </head>
 <body>
     <h1>CodeMeta generator</h1>
 
     <p>Most fields are optional. Mandatory fields will be highlighted when generating Codemeta.</p>
 
     <form id="inputForm">
         <fieldset id="fieldsetSoftwareItself">
             <legend>The software itself</legend>
 
             <p title="The name of the software">
                 <label for="name">Name</label>
                 <input type="text" name="name" id="name" aria-describedby="name_descr"
                     placeholder="My Software" required="true" />
                 <div class="field-description" id="name_descr">the software title</div>
             </p>
 
             <p title="a brief description of the software">
                 <label for="description">Description</label>
                 <br />
                 <textarea rows="4" cols="50"
                     name="description" id="description"
                     placeholder="My Software computes ephemerides and orbit propagation. It has been developed from early ´80." ></textarea>
             </p>
 
 
             <p title="The date on which the software was created.">
                 <label for="dateCreated">Creation date</label>
                 <input type="text" name="dateCreated" id="dateCreated"
                     placeholder="YYYY-MM-DD" pattern="\d{4}-\d{2}-\d{2}" />
             </p>
 
             <p title="Date of first publication.">
                 <label for="datePublished">First release date</label>
                 <input type="text" name="datePublished" id="datePublished"
                     placeholder="YYYY-MM-DD" pattern="\d{4}-\d{2}-\d{2}" />
             </p>
 
             <p>
                 <label for="license">License</label>
                 <input list="licenses" name="license" id="license" aria-describedby="licenses_descr">
                 <datalist id="licenses">
                 </datalist> <!-- TODO: insert placeholder -->
                 <div class="field-description" id="licenses_descr">from <a href="https://spdx.org/license-list">SPDX licence list</a></div>
             </p>
         </fieldset>
 
         <fieldset id="fieldsetDiscoverabilityAndCitation">
             <legend>Discoverability and citation</legend>
 
             <p title="Unique identifier">
                 <label for="identifier">Unique identifier</label>
                 <input type="text" name="identifier" id="identifier"
                     placeholder="10.151.xxxxx"  />
                     <div class="field-description">such as ISBNs, GTIN codes, UUIDs etc..  <a href="http://schema.org/identifier">http://schema.org/identifier</a> </div>
             </p>
             <!-- TODO:define better
 
             I looked at the schema.org definition of identifier (https://schema.org/identifier),
             it can be text, url or PropertyValue.
             Used as follows in data representation with microdata:
 
             <div property="identifier" typeof="PropertyValue">
             <span property="propertyID">DOI</span>:
             <span property="value">10.151.xxxxx</span>
             </div>
             we can use that with identifier-type and identifier-value to have a clearer idea
             of what needs to be in the input.
 
             -->
 
             <p title="Type of the software application">
                 <label for="applicationCategory">Application category</label>
                 <input type="text" name="applicationCategory" id="applicationCategory"
                     placeholder="Astronomy"  />
             </p>
 
             <p title="Comma-separated list of keywords">
                 <label for="keywords">Keywords</label>
                 <input type="text" name="keywords" id="keywords"
                     placeholder="ephemerides, orbit, astronomy"  />
             </p>
 
             <p title="Funding">
                 <label for="funding">Funding</label>
                 <input type="text" name="funding" id="funding" aria-describedby="funding_descr"
                     placeholder="Università di Pisa (PRA_2018_73)"/>
                 <div class="field-description" id="funding_descr">software funded by (e.g. specific grant)</div>
             </p>
 
             Authors and contributors can be added below
         </fieldset>
 
         <fieldset id="fieldsetDevelopmentCommunity">
             <legend>Development community / tools</legend>
 
             <p title="Link to the repository where the un-compiled, human readable code and related code is located (SVN, Git, GitHub, CodePlex, institutional GitLab instance, etc.).">
                 <label for="codeRepository">Code repository</label>
                 <input type="URL" name="codeRepository" id="codeRepository"
                     placeholder="git+https://github.com/You/RepoName.git" />
             </p>
 
             <p title="Link to continuous integration service (Travis-CI, Gitlab CI, etc.).">
                 <label for="contIntegration">Continuous integration</label>
                 <input type="URL" name="contIntegration" id="contIntegration"
                     placeholder="https://travis-ci.org/You/RepoName" />
             </p>
 
             <p title="Link to a place for users/developpers to report and manage bugs (JIRA, GitHub issues, etc.).">
                 <label for="issueTracker">Issue tracker</label>
                 <input type="URL" name="issueTracker" id="issueTracker"
                     placeholder="https://github.com/You/RepoName/issues" />
             </p>
 
             <p title="Related document, software, tools">
                 <label for="relatedLink">Related links</label>
                 <br />
                 <textarea rows="4" cols="50"
                     name="relatedLink" id="relatedLink"></textarea>
         </fieldset>
 
         <fieldset id="fieldsetRuntime">
             <legend>Run-time environment</legend>
 
-            <p title="Programming Language">
+            <p title="Programming Languages, separated by commas">
                 <label for="programmingLanguage">Programming Language</label>
                 <input type="text" name="programmingLanguage" id="programmingLanguage"
-                    placeholder="C#"  />
-            </p> <!-- TODO: We should add support for multiple languages, eg. by splitting on commas when exporting. -->
+                    placeholder="C#, Java, Python 3"  />
+            </p>
 
-            <p title="Runtime Platform">
+            <p title="Runtime Platforms, separated by commas">
                 <label for="runtimePlatform">Runtime Platform</label>
                 <input type="text" name="runtimePlatform" id="runtimePlatform"
-                    placeholder=".NET"  />
+                    placeholder=".NET, JVM" />
             </p>
 
-            <p title="Operating System">
+            <p title="Operating Systems, separated by commas">
                 <label for="operatingSystem">Operating System</label>
                 <input type="text" name="operatingSystem" id="operatingSystem"
-                    placeholder="Android 1.6"  />
+                    placeholder="Android 1.6, Linux, Windows, macOS" />
             </p>
 
             <p title="Required software to run/use this one.">
                 <label for="softwareRequirements">Other software requirements</label>
                 <br />
                 <textarea rows="4" cols="50"
                     name="softwareRequirements" id="softwareRequirements"
                     placeholder=
 "Python 3.4
 https://github.com/psf/requests"></textarea>
         </fieldset>
 
         <fieldset id="fieldsetCurrentVersion">
             <legend>Current version of the software</legend>
 
             <p title="Version number of the software">
                 <label for="version">Version number</label>
                 <input type="text" name="version" id="version"
                     placeholder="1.0.0" />
             </p>
 
             <p title="The date on which the software was most recently modified.">
                 <label for="dateModified">Release date</label>
                 <input type="text" name="dateModified" id="dateModified"
                     placeholder="YYYY-MM-DD" pattern="\d{4}-\d{2}-\d{2}" />
             </p>
 
             <p title="a brief description of the software">
                 <label for="releaseNotes">Release notes</label>
                 <br />
                 <textarea rows="4" cols="50"
                     name="releaseNotes" id="releaseNotes"
                     placeholder=
 "Change log: this and that;
 Bugfixes: that and this." ></textarea>
             </p>
 
 <!--TODO: referencePublication as ScholarlyArticle array -->
 
         </fieldset>
 
         <fieldset id="fieldsetAdditionalInfo">
             <legend>Additional Info</legend>
 
             <p title="Scholarly article describing this software">
                 <label for="referencePublication">Reference Publication</label>
                 <input type="URL" name="referencePublication" id="referencePublication"
                     placeholder="https://doi.org/10.1000/xyz123" />
             </p>
 
             <p title="Development Status">
             <label for="developmentStatus">Development Status</label>
                 <datalist id="developmentStatuses">
                         <option value="Concept">
                         <option value="WIP">
                         <option value="Suspended">
                         <option value="Abandoned">
                         <option value="Active">
                         <option value="Inactive">
                         <option value="Unsupported">
                         <option value="Moved">
                 </datalist>
                 <input list="developmentStatuses" id="developmentStatus" aria-describedby="developmentStatuses_descr"
                 pattern="Concept|WIP|Suspended|Abandoned|Active|Inactive|Unsupported|Moved">
                 <div class="field-description" id="developmentStatuses_descr">see <a href="http://www.repostatus.org">www.repostatus.org</a> for details</div>
             </p>
 
             <p title="Part of">
                 <label for="isPartOf">I part of </label>
                 <input type="URL" name="isPartOf" id="isPartOf"
                     placeholder="http://The.Bigger.Framework.org"  />
             </p>
         </fieldset>
 
         <div class="dynamicFields">
             <fieldset class="persons" id="author_container">
                 <legend>Authors</legend>
 
                 <p>Order of authors does not matter.</p>
 
                 <input type="hidden" id="author_nb" value="0" />
                 <div id="addRemoveAuthor">
                     <input type="button" id="author_add" value="Add one"
                         onclick="addPerson('author', 'Author');" />
                     <input type="button" id="author_remove" value="Remove last"
                         onclick="removePerson('author');" />
                 </div>
             </fieldset>
 
             <fieldset class="persons" id="contributor_container">
                 <legend>Contributors</legend>
 
                 <p>Order of contributors does not matter.</p>
 
                 <input type="hidden" id="contributor_nb" value="0" />
                 <div id="addRemoveContributor">
                     <input type="button" id="contributor_add" value="Add one"
                         onclick="addPerson('contributor', 'Contributor');" />
                     <input type="button" id="contributor_remove" value="Remove last"
                         onclick="removePerson('contributor');" />
                 </div>
             </fieldset>
         </div>
 
     </form>
     <form>
         <input type="button" id="generateCodemeta" value="Generate Codemeta" />
         <input type="button" id="resetForm" value="Reset form" />
         <input type="button" id="importCodemeta" value="Import Codemeta" />
     </form>
 
     <p id="errorMessage">
     </p>
     <pre contentEditable="true" id="codemetaText"></pre>
 
     <script>
         initFieldsData();
         initCallbacks();
         loadStateFromStorage();
     </script>
 </body>
 </html>
diff --git a/utils.js b/utils.js
index 7f413b4..4d0c673 100644
--- a/utils.js
+++ b/utils.js
@@ -1,22 +1,26 @@
 /**
  * Copyright (C) 2019  The Software Heritage developers
  * See the AUTHORS file at the top-level directory of this distribution
  * License: GNU Affero General Public License version 3, or any later version
  * See top-level LICENSE file for more information
  */
 
 "use strict";
 
 function getNbPersons(prefix) {
     var nbField = document.querySelector(`#${prefix}_nb`);
     return parseInt(nbField.value, 10);
 }
 
 function setNbPersons(prefix, nb) {
     var nbField = document.querySelector(`#${prefix}_nb`);
     nbField.value = nb;
 }
 
 function setError(msg) {
     document.querySelector("#errorMessage").innerHTML = msg;
 }
+
+function trimSpaces(s) {
+    return s.replace(/^\s+|\s+$/g, '');
+}