Which Regular Expression's engine are you recommend for Keyboard Maestro?

[JMichaelTX]

@boehmflute

By the way, I still do not understand well what is "Code Block" mean.

Did you read the Code Block link:

@JMichaelTX

How to Put Code (or Text) in a Forum Code Block

Just insert your text between the lines with the triple backquotes:

See Markdown for Code Blocks

To get syntax highlighting, then use the keyword in lower case for that language, like:
applescript
javascript
html
text

What part of that do you not understand?