Heathkit TC-3 tube checker - How to use?

[Robert Grant]

Decades ago, I inherited a Heathkit TC-3 tube checker.

Recently, I dusted it off, as I'm trying to being my old TVs and radios up to spec during the winter.

The tester came with two scrolls showing the tube tester settings for testing the types of tubes then in common use (one scroll is from about 1960, and is missing a lot of newer tubes, the other from about 1966, and some of the older tubes are dropped from the list), but there is no instruction manual with it.

The reason I'm writing this is that the tube data scrolls do not fully explain how to test the tubes. Most confusing to me, is that the lever settings are printed in two typefaces, mostly a regular serif font, but at least one lever, usually set to the bottom, being in a bold sans serif font. In some cases, parentheses get involved.

For example:
The settings for the type 6CL6 are:

3 6.3 22 (BJ)(CH) FG................AD.

Now, the first three figures are self-explanatory, but I'm lost on the difference between, say, A and A, and the difference between (CH) and merely CH.

As before, thanks in advance for any information about using the TC-3.