You can edit custom (or dynamic) attributes from either the main menu (Modify > Edit Attribute) or from the Attribute Editor (Attributes > Edit Attributes).You can perform the following editing operations on custom attributes.
In attribute names, all punctuation except for the underscore (_) and the pound sign (#) are illegal characters
For example, if you created a vector attribute named Speed, the children would be SpeedX, SpeedY, and SpeedZ. You can’t access the Numeric Attribute Properties (Keyable and Min/Max) of the parent vector attribute. You have to select a child attribute and modify its Numeric Attribute Properties.