banned_filename_re expressions

[Bill Measday]

Hi,

I've tried searching for an answer to this, but it's pretty hard to 
search for as you will see.

Could someone please explain to me in setting up banned_filename_re in 
amavisd.conf why some entries have an "i" on the end.

For example:

     qr'^\.(exe-ms|dll)$',                   # banned file(1) types, 
rudimentary

doesn't, but

     qr'.\.(pif|scr)$'i,                     # banned extensions - 
rudimentary

does.

Obviously there is logic here, but I'm missing it.  Perhaps it's a perl 
issue (I'm no good at perl).

I couldn't see anything in the docs that helped me, and any search with 
"i" in it is doomed to failure.

Thanks in advance,

Bill