Hi, Bob-

>>>A module must be coherent and it must reduce coupling. What does the word coherent mean?
>
>>Cohesive. Not coherent
>
>I'm not sure I understand your comment above. Being that cohesive means "exhibiting or producing cohesion or coherence" if something is cohesive you'd think it was coherent?

Probably. Coherent is a perfectly good word, though somewhat different in intonnation than cohesive. But the point is that we're talking about definitions and the definition is for "cohesive." If you start throwing in different words to replace the defined term, then you start to introduced vagueness or ambiguity in the discussion. So, we should stick with "cohesive."

>Also from what I understand, in software development the term cohesion means understandabilty (Is that a word?).

No, it means, basically, do the members of a component necessarily and sufficiently contribute to the responsibility of the component. Necessary means the component's responsibility would be incomplete with the member. Sufficient means the member doesn't have anything extra. ("Anything" being in the extreme of course.)

> If so cohesion would have levels, High cohesion or low cohesion.

There are levels certainly, without having to introduce the work coherent. Really, I just think there was as much a typo in the original post.

> Something with high cohesion would be easier to understand, low cohesion would be harder to understand.

Not necessarily. First, coherent doesn't mean easy to understand. It just means understandable. Makes sense. Lucidity. Stephen Hawking's theories are lucid and coherent, but hardly easily understood by most mortals. *s*

> If this is the case if something is cohesive wouldnt that be coherent?

I don't know. And, frankly, I don't really care. Discussing coherency is outside the boundries of the topic, IMO, and are philosophical, or a matter for the functional analysis. *s*