I have a number of 296 in box 14 (Other) with a code of impinc next to it. What is that, and what do I do with it?

It appears this is imputed income as explained below.

• Imputed income is the value of a service or benefit provided by employers to employees, which must be treated as income.  Because it is considered taxable income, then the employer should have included this in box 1, Gross Wages (Form W2) already. 

You can confirm this with your employer if you like, but you shouldn't have to do anything special with your tax return except to add the W2 as you normally would. Enter your box 14 amount and move forward.

this says NOTHING about what to select in category !!!

You can chose Other as a category for Box 14 entries. In most cases, the information that your employer lists in Box 14 of your W-2 does not affect your income tax return. In fact, for many Box 14 entries, the IRS does not even provide a place for it to get reported on your return forms. They are reported to you in Box 14 simply for informational purposes.