sorry, comes of being self-taught! The layer scale of the imported file was 1:0.1; I 'selected all' with 'active only' in layer options, then opened the layers dialogue box, clicked on 'scale' and then under 'enlargement' clicked on 100x; this then automatically created a new layer ('design layer two') which, in the layers dialogue box, stated that the scale was 1:100. However, if the layer options tab is set to 'active only' the screen is blank, if it's set to 'show all' it's showing the survey at 1:100. If I return to the imported survey layer, it's still saying it's 1:0.1 and measuring the external dimensions of a long wall at 13.1mm - this wall is measured at 13.1m when I return to design layer two. It's really strange! But as I said, even when I set the layer option to 'show/snap/modify' I can't actually modify the survey unless I'm on that imported survey layer, and then I'm in the wrong layer scale! I can't see any way round at the moment other than to redraw in design layer two over the existing survey, and hope that I 'trace over' in the right place... Does this make sense?
thanks for your patience in this!