Perfect, THANKS! Just to make it complete: the syntax is
inset-apply ref LatexCommand <Format> reference "<label name>"\end_inset where <label name> is the name of the referenced label and <Format> is one of the following: ref -- <reference> eqref -- (<reference>) pageref -- <page> vpageref -- on <page> vref -- <reference> on <page> prettyref -- Formatted referenceAs well on the updated function list: http://wiki.lyx.org/LyX/LyxFunctionList
Regards Toby