Depending on if the machine has run the application before you can type anything inbetween <name>XXX</name> and when you read configs the event log should tell you the known app names.
Also if you're just trying to limit the project and not the specific app you can do this:
<app_config>
<project_max_conurrent>X</project_max_concurrent>
</app_config>
And thats the whole file no names needed
<project_max_concurrent> was introduced in BOINC 7.4.9