TYPE OF
TOLERANCE
CHARACTERISTIC
AND SYMBOL
DATUM
REFERENCE
IMPLIED
CONDITION
ALLOWABLE
MATERIAL MODIFIERS
TOLERANCE
ZONE SHAPE
KEY POINTS TO REMEMBER
SIZE
SIZE CONTROL
N/A
PERFECT FORM AT MMC
REQUIRED
(ENVELOPE RULE)
PERFECT FORM AT MMC
NOT REQUIRED
CYLINDRICAL
SHPERICAL
OR
PLANAR
  1. REQUIRED FOR FEATURES OF SIZE.
  2. EACH CROSS SECTION OF THE INDIVIDUAL FEATURE (CYLINDRICAL, SHPERICAL OR PLANAR) SHALL BE BE WITHIN THE SPECIFIED TOLERANCE OF SIZE.

SIZE CONTROL:
Unless otherwise specified, this control prescribes the extent within which variations of geometric form, as well as size, are allowed. This control applies solely to individual features of size.

SIZE CONTROL TOLERANCE ZONE:
Defined by the upper and lower limits relative to a nominal value, a size control tolerance specifies the maximum and minimum boundary of a feature of size at each cross section.