Now there exists a tool which instead of filtering the
event passing HLTHighLevel, produces
a flag that can be stored in the event for subsequent use.
Instructions for its use case are given here:

Anyone who works with LaTeX knows how time-consuming it can be to find
a symbol in
symbols-a4.pdf that you just can't memorize. Detexify is an attempt to simplify this search. Here is the website where one can draw symbols by hand and then
get the corresponding html code: