Hello, I’ve found this screenshot from another page.(https://www.grasshopper3d.com/forum/topics/flattening-a-specific-layer-of)
Could someone tell what the text in the panels actually means? (“0;”&x&";*")
Is that C language? and how to make the font in italic in grasshopper?
Each panel has its own font override.
The language is the grasshopper scripting language, loosely based on VBScript.
The ampersand is the string concatenation operator.
Hi @liutianliao,
Probably means append/add x to the string "0;" and also add ";*" at the end.
For a series of for instance 0, 1, 2, 3, this would produce the following strings:
“0;0;*”
“0;1;*”
“0;2;*”
“0;3;*”
The asterisk (*) at the end probably means match anything after "0;x;", since the strings are used as search masks in the next step.
Nope, most certainly not. 
When you right-click the panel and select Font Settings > Custom Font, you can adjust the text formatting. For instance, "0;1;*" would match all these paths: "0;1;0", "0;1;1", …"0;1;10" and replace them with whatever was specified as replacement path.