^start of line
aaathe literal text aaa (case sensitive) \s+any whitespace character, repeated at least once
accounting system defaultthe literal text accounting system default (case sensitive) Non-Capturing Group(?:\s+action-type)? ?repeats the group contents below at most once:
\s+any whitespace character, repeated at least once
action-typethe literal text action-type (case sensitive) \s+any whitespace character, repeated at least once
start-stopthe literal text start-stop (case sensitive) \s+any whitespace character, repeated at least once
groupthe literal text group (case sensitive) \s+any whitespace character, repeated at least once
tacacsthe literal text tacacs (case sensitive) \+the literal + (4310 / 538 / 2B16)
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string