I’m going around in circles with Tracking Tolerances near CTA
The books still reference VFR Nm distances at different altitudes and older material references angles to single decimal point accuracy for instrument tracking. Then I hear they have all fallen by the way and the simple rule is “stay out of CTA”
What is current? Are there any more tracking tolerance rules or is it as simple as “stay out of CTA”?

It is as simple as “stay out of CTA”

The closest reference I can find is AIP ENR 1.1 para 2.2.2 in the current AIP

In the upcoming August release it's AIP ENR 1.1 para 2.1.2 (note 2) ......(Thanks Air Services)

Cheers