Datum reference letter
-Material condition symbol
fig. 3-20 feature control frame incorporating a datum reference
(a) One datum reference
(b) Two datum references
(c) Three datum references r—Multiple datum V primary
r- Primary \ y Secondary
r- Primary \ r- Secondary ^Tertiary
fig. 3-21 order of precedence of datum reference an axis established by two datum diameters — both datum reference letters, separated by a dash, are entered in a single compartment. Where applicable, each datum reference letter is followed by a material condition symbol. See Figs. 3-21(a) and 4-19 and para. 4.5.7.
3.4.3 Feature Control Frame Incorporating Two or Three Datum References. Where more than one datum is required, the datum reference letters (each followed by a material condition symbol, where applicable) are entered in separate compartments in the desired order of precedence, from left to right. See Figs. 3-21(b) and (c). Datum reference
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