[sciurius]

There's an old saying, attributed to Jon Postel: "Be liberal in what you accept, and conservative in what you produce."
The ChordPro reference implementation uses the C-library function strtok with ": " (colon + space) as delimeters. Therefore it accepts all of the following:

Code:

{columns 2}
{columns:2}
{columns: 2}
{columns : 2}
{ : columns ::: 2 : }

This also means that

Code:

{title: My Song}

specifies the title as "My Song" with no leading spaces.