cm, mm.. units in markup function

[Michael Käppler]

Hi all,
is it possible to use absolute units in a scheme markup function?

The following example doesn't work:

#(define-markup-command (iname layout props name) (string?)
 (interpret-markup layout props (markup #:combine #:hspace (* 50 mm) 
#:large name))
)

Greets,
Michael