Dimension Origin

Per ASME 2004, then later adopted in 2009, The Dimension Origin symbol is a virtually unknown in the drafting world simply do to the fact that a datum does the same thing, but with added versatility. This symbol just signifies from what surface the dimension should start.

Refer to the ASME Y14.5 2009 Fig 3-11 and para 3.3.17.

In Solidworks, All you need to do is right click on the leader display point on the dimension it's self, then select the circle from the drop down list....easy :)

Point Selection.

Drop down menu will appear.

Finished result...just like the ASME guide states.