Final answer:
In the SALUTE report, the 'Size' of the observed group is reported in the 'S' line, detailing the number of personnel or equipment present.
Step-by-step explanation:
In the SALUTE report, the size and/or strength of the observed group is reported in the 'S' line, where 'S' stands for Size. This part of the report specifies information on how large the observed group is, essentially the number of personnel, vehicles, or equipment present. Accurately reporting this is critical for intelligence purposes, as it provides a quantitative measure of the group's potential capabilities or threat level.