Is there a length limitation on file extensions?

[j.o.l]

I am using Nginx to serve a website that hosts a .Net application. The file
a user needs to download and that triggers installation is a *.application
file, and an MS Internet Information Server associates that with the mime
type application/x-ms-application. However that file never gets any
Content-Type header. I edited the mime.types configuration file to include
that, but Nginx ignores that. When I rename the file to .app, and use a mime
type definition for that file it works. I also tried various other file
extensions of varying length, and it looks like there is a limit of 10
characters in a file type extenion of Nginx, and if that is exceeded there
will be no Content-Type header.
Is my assumption correct? Where is this in the source files? (I know how to
compile Nginx). Or any other idea what causes my problem?
Thanks, Joachim

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,265148,265148#msg-265148