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Lets throw out all of the semantics for a moment so that there is no confusion by terminology. When the ECU fires the plug, it is doing so at particular moments in the rotation of the crankshaft so as to coordinate the combustion process to produce power. The ECU determines what position the crankshaft is in via the cam angle sensor, which is connected to the crankshaft via the timingbelt. When the engine is idling, the typical moment to fire the plug off is 15 degrees of crankshaft rotation before the piston reaches top dead center, or 0 degrees. In the ECU's program, there is a value that specifies this 15 degree ignition timing value when at idle, however, in order for the spark to actually fire off at 15 degrees before top dead center, the cam angle sensor must be properly calibrated. Nothing other than a timing light which shows the relationship between when the plug fires and where the crank is in its rotation. No ECU, regardless of how fancy or cryptic it is can tell you what the actual timing is without the CAS being properly calibrated.
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