Grade 0.5 gage blocks under one inch in length should have length tolerances of +/- 1 micro-inches (1 mike or 1 millionth of an inch) and flatness and parallelism variation of not more than 1 ...

It was difficult to understand how a bolt could be out of tolerance by one-inch and still fit in the baseplate holes. So the ACI embedded item tolerances for anchor bolts was considered suspect.