What is the TC/Object/Value good for?

There are no options to link to the Timecode Offset (which is what is turned on when Current Timecode is selected. Once you have access to the Value, you can set the time to whatever you need and animate the time with any other means you need.

Timecode set by 1) position of playhead graphic X parameter AND set by 2) a Custom Behavior with Add > Object > Timecode > Value. Note: Custom defaults to drop frame time and the value set by the Custom behavior will not be exactly the same time as non-drop frame time. [You could reverse the dependence of playhead position and timecode -- but if you drag the playhead, you would want the timecode to change with the position

As with all of these types of generators, the "time" is created in the project and not on "real time".

Use Custom to Set "current time" and Link an animated offset.

(note the time format in Custom - you have no choice - it's always drop frame as indicated by the ';').

Also note: time can go forwards or backwards... (sports clocks/countdown timers, etc...)

All of us "common users" of Motion have no access to time data from clips or the playhead position in FCPX (i.e., using the Timecode generator in Current Timecode mode). That doesn't have to be a deal-breaker. What would be REALLY nice would be to have a Loop Counter when Project Loop End markers are used that could be applied to parameters via a behavior or some other mechanism. In terms of a clock, we could create a 10 second project that looped, and apply the loop counter to 10's of seconds (for example) to increment a clock. Even a one frame loop that could be counted would be a huge space saver in the design and creation of timer projects for FCPX. We wouldn't need access to FCPX timing mechanisms at all.

Since you have to set time animations manually, you can depend that the time length of your project will be conformed to the storyline. You can rig some snapshots if you need to, but in general, the MOST accurate timing you will get out of Motion is with a project that is 60fps. If you want to use longer (?) frame lengths, do not use any of the fractional frame rates (23.98, 29.97, 59.94 etc.) They'll just add to your problems. If you know what the destination frame rate will be, that rate can be "targeted" (e.g.: 25.0 fps for European users).

What you might be able to do is publish the TC with Current Timecode with a toggle checkbox to turn it off once the animated timecode is "set" by the end user. That's about as good as we get. Past that: how good are you at Objective C?

I'm not sure if I answered your questions in my meanderings. Bottom line, use Current Timecode and you can display the time of the playhead in FCPX. You have no access to that time in your project. Current Timecode and Value are not connected in any way. Time depends entirely on what is created in the project. You can get a starting time from an end user via the inspector. All other animation will depend on what you can construct.

Consider a feature request for a project loop counter 😉!

You have to turn off the "Current Timecode" parameter to have access to the Value which is linkable. Once freed up, you can use it with just about any numerical parameter. The "Offset" (which is active when Current Timecode is selected) parameter is unlinkable.

Tried to reply to this last night... something broke and the entire response evaporated.

Yes - the "vice versa" advice.

Project is storyline time no matter where the generator is placed. Source is "generator time" [beginning of generator starts at 0]. It creates the displayed time, I suppose.

The discrepancy between your clock bug and timecode is probably due to lying to fcpx and telling it the time is a different frame rate than the project. If I set the frame rate to 60 in a 30fps project, the displayed time is exactly 1/2 the actual 30fps project time.

We just do not have any access to the Current Timecode from FCPX. There is nothing that will link to it. Nothing we can attach to it. We have everything we can do to control the Timecode display via the Value parameter, but that has no effect on anything in FCPX (other than what we set up to display). BTW, we can't animate the Value (keyframed) in FCPX either, but it can be used to drive animation in Motion templates (although there's really no point because Value has to be animated by another source).

About the only difference I can see in the Generator and the Effect is the effect uses "autotitles". When set to project, the project name is appended to the timecode line on a new line; when set to source, the clip name is appended.

Autotitles, I know how to do. Accessing FCPX timecode in Motion... still not finding it.