Exact matches only with the operator IS:
The string that you supply has to appear "as is" in the given field to create a hit. And to make sure that there is no room for interpretation, it is the best thing to enclose such string in inverted commas.
Sorry, I mean exact match of keyword/phrase that could be anywhere in the genre tag (ie. string); because the expression uses a HAS not IS? eg. finding 'Popular Dance' in 'Popular Dance; Pop, Dance, Grunge' genre tag (and not matching Pop).
Using IS would mean the entire genre tag can only contain 'Popular Dance'?
I'm just explaining my understanding out loud here in question form 
Yeah 
Make it a statement and that's it.
You're a legend, thank you.
How would I use parantheses in the filter expressions? Thought using them would help legibility. Examples would help, please?
Parenthesis tell that the whole filter expression is only true if all the terms in parenthesis lead to the result "true".
E.g. to find the wrong spelling of Scottish Mc:
(artist HAS mc AND NOT artist MATCHES "(?-i)Mc")
This example doesn't show the parentheses feature as it gives the same result no matter if you'd use the parentheses or not.
Parentheses are used to combine more complex logical expressions to ensure that the evaluation happens in the correct order.
(expr1 AND expr2) OR (expr3 AND expr4)
This expression exemplifies how the two pairs expr1/expr2 and expr3/expr4 are ensured to be logical AND-combined.
These examples make sense, I understand it now.
Now time to practice! Thanks guys.