The two boundaries
The upper line is typically drawn through a cluster of similar highs. The lower line rises through higher lows. Because real observations are noisy, different users may choose slightly different anchor points.
What can be measured
You can measure the vertical height of the structure, percentage width between selected points and distance from a current hypothetical value to the upper boundary. Those are reproducible calculations once the boundary values are specified.
What the name does not imply
The word “ascending” refers to the lower boundary, not to a guaranteed future direction. Price can move through either boundary or remain inside the structure longer than expected.
Synthetic study
Use the Breakout Lab to switch to the ascending-triangle example. The drawing is intentionally fictional and contains no security symbol or date, so the exercise stays about structure rather than a trade idea.