A sequence diagram shows the functionality of a piece of the system, crossing different operations. This is good, and answers the question “how is this functionality implemented”.

But developers are often used to seeing a single operation at a time, this corresponds to a vertical slice through a sequence diagram.

This review is not an indication that something is wrong, but provides an opportunity to examine how an operation is expressed through sequence diagrams.

Expresses the tmrTimer_Tick operation as:

There are no consequences to this review. It's meant from information.

If the operation pseudocode looks as you would expect ignore the review item.