[Boatanchors] Schematic Convention

[elden meyer]

 Good Morning Ron and group,
The convention I learned was that the arrow head associated with the tuning slug symbol pointed up for a top adjustment and down for a bottom adjustment.
A quick look through the CQ Surplus Schematics Handbook showed only the APS-13 diagram following this format. 
An equally brief on-line search revealed that this is not the current IEEE/ANSI practice.
Elden