Understanding the ".ini" file.

Hi Guys, just a quick one.

I want to understand the .ini file and hoping someone can help.

Under the channel headings we have
[trim1]
[gui-320x240]
[gui-128x64]

Obviously there is a lot of info under those headings, but what are they for.

Question being is if I amend the values from within the channel headings, is there anything within these 3 headings I need to amend.
thanks