mb native function $Contains can be used not only for tags, these are still correct usage: $Contains(the door open,<Artist>) or $Contains(my sample text,sample), though the latter usage (with only static text) is useless.
Hmm, I'm starting to regret asking about this ;-)
So where in my sheet it says: $Contains(<field>,search-value)
<field> is not strictly correct, since the <> indicates an existing tag should be used, while it could also be a string (text).
And in the two new functions you recently provided, the actual tag to be used must not
be embraced with '< >'
I'll probably need to reconsider how I use, name and explain entities as 'field', 'string' '< >' etc. in the sheet and the explanations.
I'm guessing it won't be easy for a newBee (or myself in a few weeks) to understand or remember the exact requirements and possibilities of all this.