Intended to simplify the display of running headers (can also be used for footers) when transcribing scanned text pages. Many texts include running headers (chapter names, etc.) centered at the top of a page, with accompanying page numbers on the left or right side (depending on whether the page number is even or odd).
3-part headers (left, centre, right)编辑
Most running headers have three parts, one on the left, one on the right and one in the centre. If the template is given 3 arguments or fewer, they correspond to the left, center, and right sides of the running header.
The template may be called using implicit parameters, in which case the order is left, center, right. For example:
Alternatively, it may be called with explicit parameter names. For example:
The use of explicit parameter names is especially useful in cases where one or more parameters are to be omitted.
4-part headers (left, left-centre, right-centre, right)编辑
Some works, escpecially dictionaries and directories, have two headings in the centre of the page, one to the left and one to the right. In this case, you can provide 4 parameters, corresponding in turn to the left, left-centre, right-centre and right parts of the header.
If a fourth parameter is present but blank, it will still trigger a 4-part header: