Logical Editors

Thanks LoveGames. The sample offered is much too complicated for a beginner, although it would help an intermediate person. This is borne out by the puzzlement in the comments.
Interestingly, the embedded link to the Steinberg manual Using Brackets shows one of the examples which is not correct.
The second example is fine. But the first one wouldn’t work as described; the OR on the third line would return MIDI AND Audio tracks and anything else which contained the string drums (or Drums or DRUMS, as the Logical Editor string search is case-insensitive).

Sorry about all the Tabloid-style UPPERCASE and bold and italics, but I have found that these help to draw the eye to the more important bits.
I may have to amend it; I always notice mistakes on re-reading after publishing.

I have a Cubase Project with Audio and MIDI tracks whose names contain the string “melody”, and Audio and MIDI tracks whose names contain either the string “harpsichord” or the string “harmony” .
I have tried the following examples in the last 20 minutes.

This one has the same structure as Example 1 in the Operation Manual:
( Media Type is Equal Audio and
Name contains Melody or
Name contains har )
Action:
Set Color to fixed value Color 8 {light green}

The tracks which change colo(u)r are:
Audio Tracks containing “Melody”
MIDI AND Audio Tracks containing “har”

The manual says (Quote) “you can set up the Project Logical Editor to find all audio parts and events whose name contains perc as well as other MIDI parts and events whose name contains drums” . That’s NOT what happens, as Audio Parts whose names contain the string drums WOULD ALSO be selected and given the colour Color 8 (or whatever colour was chosen).

I then added the nesting brackets for the OR.

This one has the same structure as Example 2 in the Operation Manual:
( Media Type is Equal Audio and
( Name contains Melody or
Name contains har ))
Action:
Set Color to fixed value Color 8 {light green}

The tracks which change colo(u)r are:
Audio Tracks containing “Melody”
Audio Tracks containing “har”
That IS as described in the Manual.

The initial AND will always constrain the line immediately after it, in this case Name contains Melody .

In Example 1, however, because the subsequent OR is not nested with brackets, it is not tied to the AND. Therefore the third line acts on its own and delivers results without regard to Media type.

Like I said, I have just tried both structures several times, and I believe the evidence of my own eyes.

Trevor