# Permitted characters

Publican uses data in this tag to generate part of the file name for RPM packages, unless overridden by data in the `publican.cfg` file. If you do not override this tag in the `publican.cfg` file, this tag must only contain upper- and lower-case un-accented letters, digits, and the hyphen-minus, period, underscore, and plus characters (‘a–z’, ‘A–Z’, ‘0’–‘9’, and ‘-’, ‘.’, ‘_’, and ‘+’) if you plan to build packages with Publican.