Redefining the Ordinate Dimensions References
You can redefine the references of ordinate dimensions in the following ways:
Right-click and select Edit Attachment on the shortcut menu to redefine the reference of an ordinate dimension in the ordinate dimension chain.
On the Annotate tab, in the Edit group, you can click Attachment option and select the dimension to redefine the dimension reference.
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You can redefine the references of ordinate dimensions that were created as linear dimensions and later converted to ordinate dimensions.
You can also redefine the reference of the dimension that you first created in the ordinate dimension chain.
While redefining references, an error message is displayed when you select a reference that is not parallel to the ordinate baseline.
You cannot redefine the references of multiple dimensions.