Mac and file-types

[kweto]

Hello,   I'm looking to convert a stack from Windows to Mac.   Here's the question. The stack I made works with file extension suffixes (eg, ".jpg", ".gif")) to restrict which files get displayed. To do this I use a script line something like:   if char -1 to -4 is ".jpg" then ...   Can I assume file extensions identified in this way will also work as is on Macs? If not, how would I I.D. file-types on Mac?   Thank you.   Nicolas Cueto