We have framed a rough opening for the doorway in which we plan a threshold.

Here are not quite twenty questions:
Do we attach the threshold to the floor and then trig the casing within the rough opening and over the threshold?

Do we attach the threshold to the (bottom of)casing, and trig it has a unit in the RO?

Do we install the casing and then fit the threshold within the casing and on the floor?

We've tried to find sketches or diagrams of doorway construction using thresholds, bot so far, we've hadd no success.

Any advice would be most appreciated.
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