Are the following sentences grammatically correct?

1. This is a computer for educational purposes, not a computer for playing games.

2. They decided not to go a head with the plan A, meaning they may change the entire approach to the project.

3. That was the intention, to help you through the crisis.

If they are, then what kind of phrases are the bolded parts?

I have searched the net about phrases but the sites I ran into weren't very helpful with my cases. If you know a site that may be helpful, please let me know.

Thanks in advance.

Hi, vcolts. Welcome to English Forums. Thanks for joining us. [<:o)]

Your sentences are okay by me.

Have you read any articles on the appositive?

I've been on the site for about three years, and I've only been aware of one individual who has made a study of this, or expressed more than a passing interest in it.

Best wishes, - A.
Hi, Avangi. Thanks for the welcome.

I did read some articles on the appositives and the examples I provided don't seem to be model cases of appositives.

The first one and the third one could be considered as, but the 2nd one could as well be an absolute, right?