xla vs xlam addin, what is the difference?
add-in, excel, vba
Solution
The m stands for macro-enabled which is the new format (as from Excel 2007). These are add-ins that may call macro's. On the other hand, you could also have xlax extensions, which are meant for macro-freeworkbooks.
Note also the difference between xls and xlsm, where xlsx files also don't contain macro's.
Why? My guess is that the main reason would be security. Some people don't like to receive files, not knowing if there are potentially harmful macro's in it. In the old format, you could not make the distinction based on the file extension.
Problem
Could someone please explain the difference between an xla Excel addin format and an xlam Excel addin format? Googling didnt provide anything useful.