Rationale

ASTM D1238 section 6.4.2 & 6.6 (Timing and piston scribe marks). (1): Tolerances for timing system is given in seconds, with manual reference standards the uncertainty of measurement is much higher than the tolerance. Proposing a change to tolerance in percentage of total measurement and implementing a minimum measurement time span to lower the impact of measurement error. (2): Scribe marks from 6.4.2 do not have a given tolerance, proposing to add a tolerance mimicking ISO 1133-1.