Ansi B92.1a-1976 Access

: Differentiates between "effective" tooth thickness/space width (accounting for manufacturing variations) and "actual" measurements. Legacy and Current Status Spline Standards and Data Overview | PDF - Scribd

is a supplement to the ANSI B92.1-1970 standard, which provides technical specifications for involute splines and inspection . This standard is widely used in the design and manufacturing of mechanical power transmission components, such as hydraulic pumps, motors, and drive shafts. Technical Specifications Ansi B92.1a-1976

Why was it retired?

The standard covers both (teeth on a shaft) and internal splines (teeth inside a hub or bore). such as hydraulic pumps