TL;DR

This post is about common software bugs related to sequence control. The post is aligned with the Black Box Software Testing Foundations course (BBST) designed by Rebecca Fiedler, Cem Kaner, and James Bach.

A sequence is a list of statements:

INPUT A

D = A + B + C

B = 1

C = 3

PRINT D

This sequence has a typical error in the second line, we use variables B and C that are not yet defined.