Thanks for the reply.
Unfortunately, surveyor's angular measurements don't do what I need.
I need a means of defining ordinate dimensions referenced from a single point with East and North vectors coupled with dimensions from the surveyors grid origin defining the location of the setting-out points.
The ArchiRadar Locator tool does work, but the surveyor's grid (and therefore the model) need to be positioned in the model such that the surveyors grid base point (0,0) is sited at the project (ArchiCAD) origin, and that the model and surveyor's grid are correctly orientated.
This is nowhere near as good as AutoCAD's ordinate dimension tool which relates all ordinate dimensions to the current UCS - still you can't have everything I suppose.
I might add this to the wish-list if somebody hasn't already done so. Of course, if there is already an answer in ArchiCAD's tools, I would be delighted to be enlightened!
Mike