B.17.3 | The `calc` Package

LATEX source and documentation.
This package enables using traditional, infix, notation for arithmetic operations inside the num argument to the `\setcounter{`name`}{`num`}` and `\addtocounter{`name`}{`num`}` constructs (see [LATEX-bis, Section A.4])
The `calc` package provides a similar extension of the syntax of the len argument to the `\setlength` and `\addtolength` constructs. HEVEA does not implement this extension, since it does not implement length registers in the first place.