Dear Andrew,

Here is a simple question which must have a simple answer. I have defined

FLT seems to prove the opposite. Unfortunately the same is true for
your problem.

function for these elements so I wrote a Ops.Length function which of
course doesn not work. Evidiently functions like "Print", "+" and so on

'Length' only works for GAP lists, there is no way (*, at the moment)
to use it together with records. This behaviour might be considered a
bug or an annoying feature and it is possible that this will be
changed in future releases (GAP 4.0).

Do you want to create a new type of lists or just a new type of
objects? In the latter case it might help to use 'Size' instead of
'Length'.

Incidently, unless I have missed it the description of such

The description is in "Operations for Records" and the following
sections.

things does not appear to be in the manual. Similarly for the use
of "arg" in function definitions. Are these documented anywhere?

See "Function Calls". But yes, it is easy to miss something in >1000
pages. We try to reorganise the manual, but this is a *major*
project.

best wishes
Frank

==
* = short of defining a dispatcher for Length in GAP, which will slow
down almost all computations.