• An absolute URL
• An atom (interpreted as a file name)
• A term File:Line
• A term File:Line:Column

There is no official standard for encoding the Line and Column. We emit

``file://AbsFileName[#Line[:Column]]``

Both Line and Column count from 1, as in the messages we print and as used by e.g., rg --hyperlink-format=.... Note that a capital L before the line, as used by GitHub, is accepted by Epilog as well.

The sequence is emitted if and only if the Prolog flag hyperlink_term is true and Stream has the property tty(true). ansi_format/4 is guarded the same way for color_term, so that a message captured using with_output_to/2 is plain text.

See also

https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda