Currently, the datum properties dialog box shows 3 buttons: a regular datum, an ANSI Y14.5M-1982 datum and an ASME Y14.5M-1994 datum. Users frequently mistake these sybols to mean that if you select one of these buttons, the datum will conform to that standard. Unfortunately, the ASME Y14.5M-1994 style button creates an annotation that cannot be hidden on a layer and frequently does not show up correctly in drawings.
After filing a tech support case I found that PTC actually intends is that the ANSI Y14.5M-1982 datum style button is used for 2D drawing annotations and the ASME Y14.5M-1994 style button is used for 3D datum annotations. The layer issue with the ASME Y14.5M-1994 style selection (3D annotations) is in debate whether it will be fixed in Creo 4.
PTC please change the confusing symbology in the datum properties dialog box so that it differentiates between 2D and 3D annotations without confusing users with ANSI and ASME standards.