Frequently Asked Questions (FAQ)

Installation and access

HTML preview and presentation of data

Using the editor

Customizing the MerMEId editor



Installation and access

Can I install MerMEId on my laptop?

In principle, yes. Please note, however, that MerMEId is a web application, not a desktop application. This means that it needs a web server to run; the user interacts with MerMEId through a web browser. It also means that installation requires the skills of a system administrator to set up all the components of the web server. Technically, it is possible to do it on a laptop, but usually that's not advisable, because your installation and your data wouldn't be accessible from any other machine. Also, if your laptop crashes or is stolen, you are likely to lose your data. Installation on a proper web server located at your institution gives you much better data protection, and not least: You will be able to use MerMEId and access your data from any computer that has access to your server. All you need is a web browser.

Can I use The Royal Library's MerMEId server for our project?

Unfortunately no. The Royal Library's demo installation at is meant for demonstration only. The library cannot host other projects' data. You are welcome, on the other hand, to use the demo installation to try out MerMEId or even to do preliminary work until you have set up your own server. Note, however, that the library does not take any responsibility for any loss of data stored on the demo server. The data at the demo server are freely accessible for anyone to edit or even delete. If you are doing any serious work there, make sure to make local copies of your data frequently (See: How do I copy or move my data from one MerMEId instance to another?). We are also likely to clean up the server by deleting user data every now and then. If there is something you would like us not to delete please let us know.

How many MerMEId installations do I need for my project?

Preferably only one. MerMEId is a web application (See: Can I install MerMEId on my laptop?), and your data will need to be stored on the same server. If you have more than one installation, you will have trouble synchronizing your data across MerMEId intances (probably by copying files back and forth manually).

How do I copy or move my data from one MerMEId instance to another?

To move or copy XML data files from one MerMEId installation to another, download your files to your hard drive first. You can do so one file at a time by right-clicking (on Windows machines) the file's XML icon in the file list and selecting "Save as..." or equivalent. If you need to download many files it will probably be easier to use the eXist database's admin client. You will need to have administrator access to the database in order to use it. You will probably find the adminstration page at http://[yourservername.yourdomain]:8080/exist/. Click the 'Collections' option to open the database's file manager which allows you to download all or some of your files. You will find your files in the 'dcm' folder. Use the same component on another server to upload your data (again, to the 'dcm' folder).

What if some day MerMEId is no longer maintained? Will I lose my data?

No. One of the core ideas of MerMEId is that it produces data compliant to the MEI XML schema – an open, well-documented standard for encoding musical information. Basically, MerMEId is simply a user interface to allow you to produce MEI XML without having to hand-code everything. You can use other tools such as a generic XML editor to do the same, just in a less convenient way. So even without MerMEId, you can still have valid MEI XML data and continue your work using other tools. Just make sure always to keep a copy of your data somewhere safe.

How do I know which MerMEId version is running on my server?

To see the version (revision) number of your installation, open any file in the editor (or create a new one) and click the MerMEId logo logo in the lower right corner.

HTML preview and presentation of data

Can I change the way MerMEId displays my data?

Even though MerMEId can produce HTML to display your data (either by clicking a work's title in the file list or by clicking the 'View as HTML' icon in the editor), MerMEId does not tell you how to present your data to the public or in any other context. The built-in HTML preview is meant for reviewing your data for convenient proofreading etc. You are welcome to re-use or alter the XSL style sheet used to create the preview for your presentation, but more likely you will want to define your own. There is no forced connection between the way MerMEIds displays your data and the way your final presentation does. In the public version of the Catalogue of Carl Nielsen's Works (CNW), we are using MerMEId's HTML preview style sheet to do the basic formatting; we have just added a supplementary XSL style sheet to override some formattings and to filter out certain information. You can download MerMEId's basic MEI-to-HTML XSL style sheet at You may also want to download the corresponding CSS style sheet.

MerMEId does not show some information I have entered. Why?

The built-in HTML preview is designed to display all the information you may enter in the editor, with a few exceptions. Some information is very complex to handle; for instance, only some of the possible relations between sources, versions etc. are pre-defined to have a visible effect in the HTML preview. If you want other relations to have a an effect, you will have to define it in your presentation. Another example is a person name's reference to an authority file. This information is usually not intended for displaying directly; instead, projects may use it for linking to other resources. There is no obvious way of displaying it (other than a link to the file, which would be useful only for verifying that the reference is indeed correct; we might consider implementing that in the preview). Finally, there is definitely a chance that we have simply forgotten to implement a certain feature in the HTML preview because we haven't used it yet. Please let us know if something is missing.

Using the editor

How do I start a new file collection or catalogue?

You may have noticed the use of 'Collection' names in MerMEId's file list, for instance, 'MerMEId Demo'. The collection names are intended to enable you to distinguish or select files belonging to a certain catalogue in your database. This makes it possible to have any number of catalogues in the same database. To make your file part of a specific catalogue or collection, open the file in the editor, go to the 'File' tab, and enter the collection name in the field labeled 'File Collection' under 'Series' (and save your work, of course). In the file list, you will now see the collection name in the 'Collection' column, and it will also appear in the collection drop-down list, allowing you to search for files in that collection only. 

How do I make MerMEId recognize a certain number as a catalogue work number?

You may have noticed that the demo files in MerMEId's file list are labeled like'MerMEId Demo 3' in the 'Collection' column. To make MerMEId recognize a number as the work's or file's number in your collection (equivalent to the numbers in the BWV, for instance), go to the 'Work' tab, add a work identifier (under 'Identifier'), enter the file collection's name as the list name and the desired number in the 'No.' field. If MerMEId finds a work identifier corresponding to the file collection defined at the 'File' tab, it regards the identifier's number as the catalogue number.

Customizing the MerMEId editor

Can I add fields to the editor form or alter existing ones?

In principle yes, if you know how to write Orbeon XForms. You will find the MerMEId source code at GitHub. You are free to change it to make your customized version of MerMEId. However, note that this will require you to make the same changes again after installing one of our MerMEId updates. Also, MerMEId is based on sharing. No one else will benefit from your changes if you keep them for yourself. Therefore we would like to encourage you to share your improvements either by forking the code at GitHub and submitting a pull request or to discuss your wishes with us; if we agree that the changes will be of general interest, we may be willing to implement them if we have the time. Another possibility is to pay us (that is, the Danish Centre for Music Publication at the Royal Library) to make the desired improvements. That's a great way to support the MerMEId project. 

Can I change the pre-defined instrument names?

Yes. The simplest way is to manually change the text MerMEId inserts in every instance. The more efficient way is to change the instrument name list (instruments.xml), which is kept in the eXist database in a folder named 'Library' together with other lists for more convenient customization. Ask your system administrator about how to access and edit the files. The structure of the files should be pretty self-explanatory.

The authority file I use is not listed. Can I add it?

Yes. You can edit the list the same way you would change pre-defined instruments names.

How do I make MerMEId recognize other abbreviations?

The same way you would change pre-defined instruments names.

How do I change the genre keywords in the 'Keywords' menu?

The same way you would change pre-defined instruments names. The keyword file ('keywords.xml') has two sections: first, a list of hierarchically ordered keywords (called 'level 1' and 'level 2' terms); second, a list of unordered supplementary keywords. The two-level ordered list of genre terms is useful if you intend to order your files by genre at some point or enable users to browse your catalogue by genre. That's how we generated the genre menu in the CNW.


I have published a file from the file list, but nothing happens except that the 'Publish' indicator turns green. What is supposed to happen?

There's no way we can predict how and where you want to publish your data. By default, therefore, MerMEId does nothing but copying the selected file(s) from an eXist database folder named 'dcm' (where all your data are stored) to another folder named 'public'. It is up to you or your system administrator to decide what is going to happen next. At DCM, we have set up a script that automatically copies all files from the 'public' folder through the firewall to the published catalog on the web once a day. The script is not part of MerMEId, but you are welcome to contact us if you would like to know in detail how it works.

I would like to make a web catalog like the CNW. Is the user interface included in MerMEId?

No. MerMEId is a tool for creating and editing the XML data for a catalogue of works or sources, not a presentation tool. We're quite sure that every project will want to have their data presented in their own way, so we haven't made our presentation part of MerMEId. To create the public CNW catalogue, we basically use MerMEId's MEI-to-HTML transformation, add a few exceptions and alterations on top of it. We have added a few XQuery files for the search facilities and a couple of flat HTML files for the text-only pages. A few more XQuery scripts wrap the pages with a header and a footer. We are happy to share the code with you if you like.


How do I stay informed about changes and updates?

We recommend that you sign up for MerMEId news. There's a subscription form at DCM's MerMEId project page (in the right column). Don't worry – we will not flood your inbox with mails. We will send a mail only when releasing major upgrades or if there are other important MerMEId-related announcements.
A list of important information about releases, transformation of data, and known issues is compiled at
Finally, you may also want to follow the discussions about the development of the MEI schema which defines the structure of the (meta-)data produced by MerMEId. The MEI community even has a special interest group concerned with cataloging and metadata with its own mailing list where discussions regarding the encoding of musical metadata take place. Important MerMEId announcements will be posted there as well.

How do I get in touch with you if I have other questions?

For general enquiries, questions about the user interface or the MEI encoding please contact Axel Teich Geertinger. For questions regarding installation, maintenance and updates please contact Sigfrid Lundberg. For general information about the Danish Centre for Music Publication please refer to our web site.