How to generate DataMatrix tags (aka sticker sheets)

Gather all your student data into one place:

Start a new spreadsheet in LibreOffice Calc (Excel works too), with the column headings "last_name", "first_name", and "homeroom". Save it as a CSV.

Merge your student data into the new spreadsheet. For the homeroom field, you may need to get inventive. For this example, I used a "<year><a for AM, p for PM>" format. dmtag doesn't really care what this is; it just makes sorting them easier.

Add some generics on the end. I use 0 for the generic's homeroom so that when we sort it later, they come to the top.

The order of the cards on the sheet will be exactly the same as the order in this document. Thus, you should sort it. In LibreOffice Calc, this is accomplished by selecting the columns, then going to Data > Sort. I sort by homeroom, last_name, then first_name.

Start dmtag.

On the Generate tab, add a batch (not a job) by specifying the file to upload and the school code.

After a while, it'll finish. Save the outputs.

Possible problems

Accented characters

Characters like "é" (namely characters outside the ASCII Printable Characters) in the input CSV will cause dmtag to choke. The workaround is to find and replace these characters with their non-accented equivalents.

I've got a bugfix for this, but have yet to distribute it.