This is a bit of a repost, but I'm convinced many Houdini Ites would appreciate
access to a H19 hotkey summary.

Apparently older versions of Houdini came with a Houdini reference card file called “houdini_qrc.pdf”.
I did a file browser search in the installed "C:\Program Files\Side Effects Software" folder but not found.
Also, supposedly the online docs have a quick reference entry, but I can't find it.

Anyone?

here is a fairly recent site for Houdini Shortcuts that might be useful to you. https://tutorialtactic.com/keyboard-shortcuts/houdini-shortcuts/ [tutorialtactic.com]