org-property-re

org-property-re is a variable defined in `org.el'.
Its value is

"^\\(?4:[ 	]*\\)\\(?1::\\(?2:.*?\\):\\)\\(?:\\(?3:$\\)\\|[ 	]+\\(?3:.*?\\)\\)\\(?5:[ 	]*\\)$"

• This variable may be risky if used as a file-local variable.

Documentation:
Regular expression matching a property line.
There are four matching groups:
1: :PROPKEY: including the leading and trailing colon,
2: PROPKEY without the leading and trailing colon,
3: PROPVAL without leading or trailing spaces,
4: the indentation of the current line,
5: trailing whitespace.