It's the first result on Google: http://docs.python.org/library/stdtypes.html#string-formatting
See also the new format() function: http://docs.python.org/library/stdtypes.html#str.format
In docs.python.org Topic = 5.6.2. String Formatting Operations http://docs.python.org/library/stdtypes.html#string-formatting then further down to the chart (text above chart is "The conversion types are:")
My comment: help does not include attitude which is a bonus. The attitude post enabled me to search further and find the info.
Source: Stackoverflow.com