How to Write to a Position in an Array Variable

[August]

@griffman

the expression captures the first field as $1, then doesn't capture the field to be replaced, and captures everything after that as $2.

When did KBM change RegEx syntax to use $1, $2, etc. instead of \1, \2, etc.?

Earlier this evening I was looking at a macro by @JMichaelTX, Check for duplicate lines in a variable and remove, posted June 23, 2020, which used the following RegEx syntax:

Reading that example, it was clear to me that it should have been

\1\2\3\4

But I did not realize that it should have been

$1$2$3$4

instead.

Was @JMichaelTX's post using the wrong syntax at the time, or did KBM change at some point since then?