2.1.553 Part 1 Section 17.18.78, ST_Shd (Shading Patterns) 2.1.554 Part 1 Section 17.18.80, ST_SignedHpsMeasure (Signed Measurement in Half-Points) 2.1.555 Part 1 Section 17.18.81, ST_SignedTwipsMeasure (Signed