Hi, thanks for asking,
it’s not all that clever to be honest - it’s just as I provided in the examples, the expansion follows the capitalisation the author provides. So:
Lmk becomes “Let me know”, but
lmk becomes “let me know”.
it’s useful of course because you use these phrases in different parts of sentences. You might start off “Lmk what you think...”. Or at the end of a sentence; “... lmk if you agree”.
lMk would become “let Me know” (not as useful but shows the format).
As i mentioned, Textexpander has this as a specific optio