Gears Format String

format-string ::= "|" <`parameter`> [":" `format-spec`] "|"
parameter     ::= <integer>
format-spec   ::= [`align`][`fill`][`width`]["." `precision`][`verb`]*
align         ::= "<" | ">" | "^"
fill          ::= "'" <any character>
width         ::= <integer> | "*" <integer>
precision     ::= <integer> | "*" <integer>
verb          ::= "f" | "e" | "x" | "b" | "o" | "d" | "u" | "p" | "t"