If there is no newline at the end of a DC file, its last line will be ignored. Most editors create final newlines automatically, so the situation where this bug appears is surprisingly rare. However, it is still easy to reproduce:

1. Create a DC file without trailing newline char: echo -n 'MAIN=some_doc.xml' > DC-test

2. Validate your document:

   > daps -d DC-test validate 
   ERROR:  is an unsupported file type (.)
   must be ASCIIDOC (.adoc) or DocBook (.xml)
   

Counter-example

1. Create a DC file with trailing newline char: echo 'MAIN=some_doc.xml' > DC-test-good

2. Validate your document, note that you get a different error message that actually relates to the file we wanted to build:

   > daps -d DC-test-good validate 
   ERROR: Source files must reside in an "xml/" directory. "/home/sknorr-l/data/gits/sbp/xml/some_doc.xml" is not a valid location.