Please decipher this string

Support
1

I’m new to Mp3Tag. Could someone please explain each “section” of this string? (E.g. what does the “64” do? This is converting Filename to Filename. Adding a letter to the beginning of the filename. Thanks for your help.

Old Filename pattern
%1 - %2 - %3

New filename pattern
$char($add($num(%1,1),64)) - %2 - %3

2

Here is the documentation about scripting functions:

See this external page which shows the ASCII codes:

64+1 = 65 -> code for character A.