Indefinite article before "format"

I need to use this word with the following meaning:

the way in which data is stored or held to be worked on by a computer

This particular dictionary doesn't say anything about whether this word is countable or not. The given example though contains an indefinite article:

The images are stored in a digital format within the database.

So, it is supposed to be a countable noun. But when I reviewed some other examples I've discovered that putting an indefinite article along with the noun is not always the case:

However, neither the raw nor the processed data were provided in digital format.

No data were reported in digital format.

Could you please clarify the cases for me?

Solution 1:

You can use all three versions, as you choose: store it in TSDB format, store it in a TSDB format, or store it in the special TSDB format. The subtle differences:

• in TSDB format: common geek speak.

• in a TSDB format: this suggests you are talking to a non-specialist.

• in the special TSDB format: this suggests that earlier in your communication with the person, you explained something about the TSDB format, and now you are referring back to that.

I would choose among these based on how well versed the other person is with this format.