Joining the discussion over here to add a couple of points that I haven't seen in Raymond's PEP updates on the checkin list: 1. The Single Unix Specification apparently uses an apostrophe as a flag in prinft() %-formatting to request inclusion of a thousands separator in a locale aware way [1]. Since the apostrophe is much harder to mistake for a period than a comma is, I would modify my "just a flag" suggestion to use an apostrophe as the flag instead of a comma: [[fill]align][sign][#][0][width]['][.precision][type] The output would still use commas though: format(1234, "8.1f") --> ' 1234.0' format(1234, "8'.1f") --> ' 1,234.0' format(1234, "8d") --> ' 1234' format(1234, "8'd") --> ' 1,234' 2. PEP 3101 *already included* a way to modify the handling of format strings in a consistent way: use a custom string.Formatter subclass instead of relying on the basic str.format method. When the mini language parser is exposed (which I consider a separate issue from this PEP), a locale aware custom formatter is going to find a "include digit separators" flag far more useful than the overly explicit "use this thousands separator and this decimal separator". Cheers, Nick. [1] http://linux.die.net/man/3/printf -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia ---------------------------------------------------------------