that's a good question ...
Greetings Jeff ...
yes, what you've described is entirely possible ...
let's take the example bit that you mentioned (N10:1/1) as an example and look at the figure I've attached below ...
suppose that we've just done a properly formatted "Find All" search for N10:1/1 ... the results window clearly says that the bit was "Not Found" ...
suppose that next we open up the "Usage" feature – and set the Radix to "Binary/Subelement" to display everything down to the individual bit level ... we see that bit N10:1/1 (highlighted in blue) does NOT have an "X" on it – so it certainly appears that the bit we're interested in is not being controlled (or even "used") anywhere in our program ...
(I've included N10:3/3 as an extra example bit controlled by an OTE just to show what a "Used" bit would look like on the same window) ...
so ... the bit N10:1/1 is "guaranteed" to be free and clear and OK for us to use – right? ...
well, not so fast ... now check in the often overlooked "FW" column of the chart ...
the "F" code located on the row with N10:1 tells us that all of the bits on that row are subject to being used at the "File" level ... that's the COP command who's doing that ...
the "W" code located on the row with N10:1 tells us that all of the bits on that row are subject to being used at the "Word" level ... and that's being caused by the MOV command ...
so ... the lesson to be learned here is to carefully check under every single rock when you're trying to track down how an address in your program is being used ... as you might expect, this is one of the many lessons that I constantly drill my students on ... it's very easy to get caught up in the magic of the moment and miss something important if you're not paying attention to what you're doing ...
I hope this helps ...
