"Is there a similar document for the stencils that you have described?"
Yes, the Plates within Section L of the AAR Manual of Standard and Recommended Practice.
"I often see this bar-ball stencil with or without lines above and below, and another common door stencil is a circle with a vertical line. Also a bar-ball with vertical lines on each side. (Which I always thought meant the car was equipped with movable bulkheads.)"
Plate 42-A was adopted in August of 1946. The figure was a 5" diameter ball centered over a 10" long x 3" high solid bar. Applied, the figure signified cars equipped to handle auto parts.
In 1959 the Car Construction Committee was requested to develop figures which would signify cars equipped with Evans DF, Spartan Tri-Belt and Transco S-L load restraining devices.
The figure developed to signify cars equipped with bar type restraining systems (as above) was the same as 42-A with the addition of two 7-1/2" long x 1-1/2" high bars placed horizontally above and below the key slot.
The figure developed to signify cars equipped with movable bulkheads was the same as 42-A with the addition of two 7-1/2" x 1-1/2" vertical bars bracketing the key slot.
At that same time Plate 42-A was incorporated into the same grouping with the caption, "Method of marking cars equipped for handling containers."
The figures (presented as Plate 42-B) were approved and became effective on March 1, 1960.
The circle with the vertical bar was Plate 42-D adopted in 1953. The figure was a 6" inch in diameter x 1" thick circle with a 1" thick vertical bar. The figure was stenciled on cars equipped with permanent lading strap anchors.