The scales recommended for use with the metric system are:
Decimal multiples of these base scales are also used. eg. 1:100, 1:250, 20:1
Indication of Scale
The scale should normally be noted in the title block of a drawing.
When more than one scale is used they should be shown close to the views
to which they refer, and the title block should read 'scales as shown'.
If a drawing uses predominantly one scale it should be noted in the
title block together with the wording 'or as shown'.