GD&T Datum Shift

Two separate allowances stack up. Bonus comes from the toleranced feature departing its MMC. Datum shift comes from the datum feature departing its MMB — and it only exists if the datum carries an Ⓜ in the feature control frame.

Important distinction: bonus tolerance applies to the individual feature, but datum shift moves the ENTIRE pattern relative to the datum — it cannot justify one hole being out of position relative to its neighbours.