This is the file ForumStuff/sortspec so by definitions the . refers to that main folder in the test vault. So the main sorting is related to that, and it says the following:
/:files – Create a new group related to the files, and…
< true a-z – sort these files in ascending order based on the true alpha-numeric sort (this means is related to how it would sort stuff like a1b, a2b and a10b)
/folders – After all the files have been listed, I then want to sort the group of folder, as
> a-z– Normal descending natural alphabetic order. (For me that would be that the folder f58 would come before the f57 folder)
% – Do all other stuff (if any present)
sortspec – Store the sortspec file itself at the very end of this group
Notice that for each group you need to be very careful with spaces, so sorting-spec is without spaces in front. Then target-folder and the group definitions and its sorting specifications have one space in front. Finally the specification related to the /:files and /folders they’ve got two spaces in front of them.
target-folder: ForumStuff/f51/f51093– Define the folder to sort
f51093 Combine md-files – Lift out this particular file to the top of list. Any file name specified are lifted out of the order specified related to this folder
> true a-z – True descending alphanumeric sorting of the other files. That is z first down to a at last. This is just for demonstration purposes in this post
target-folder: ForumStuff/f51/f51109 – Yet another to folder somehow
> modified – Files are sorted related to last modification date, descending >. So that means, the last modified file is on top, with descending modification dates down the list.