\newlength ¶Synopsis:
\newlength{\len}
Allocate a new length register (see Lengths). The required argument
\len has to be a control sequence (see Control sequence, control word and control symbol), and as such must begin with a backslash, \ under
normal circumstances. The new register holds rubber lengths such as
72.27pt or 1in plus.2in minus.1in (a LaTeX length
register is what plain TeX calls a skip register). The
initial value is zero. The control sequence \len must not
be already defined.
An example:
\newlength{\graphichgt}
If you forget the backslash then you get ‘Missing control sequence inserted’. If the control sequence already exists then you get something like ‘LaTeX Error: Command \graphichgt already defined. Or name \end... illegal, see p.192 of the manual’.