What does the "sub" entry of a key mean?

[Bo Berglund]

On Sun, 16 Jan 2011 14:06:50 +0100, Werner Koch <wk at gnupg.org> wrote:

>On Sat, 15 Jan 2011 21:21, jrollins at finestructure.net said:
>
>> describes in detail the meaning of the --with-colons output.  It's
>> exactly the reference you're looking for when writing a program to parse
>> the --with-colons output.
>
>FWIW, gpgme provides a reference implementation for it.  In general I
>suggest to use gpgme because it provides a well maintained API to GnuPG.
>Many programs use gpgme; Debian lists 37 direct dependencies.
>

What is gpgme? I found a very short reference on the GPG website:
http://www.gnupg.org/gpgme.html
But it talks about a "library" that applications should use to access
gpg. What does "library" mean?
I looked at the download, but it looks like a source tree for some
kind of C program. :-(

I am programming in Pascal (Delphi or Lazarus with FPC).


-- 
Bo Berglund
Developer in Sweden