@Paradox yeah, SREs are not mathematical REs but a computational tool http://doc.cat-v.org/bell_labs/structural_regexps/se.pdf
@niplav Hm. So the context seems to note that they arise from the inflexibility of line-by-line text systems. They're conceived to be more... structure agnostic? Like the example they use is basically ascii art where blanks and fills are broken by newlines, but they want to parse while ignoring newlines.
@niplav I know what regex is, I didn't know they had structured and non-structured forms.