Three characters on the .org in the letter-digit-letter shape, which reads cleanly and types fast.
I3P has no single entrenched meaning, leaving it open for an organisation to claim. Institute, innovation, or information on the I; partnership, programme, platform, or policy on the P. Those are the most common words in institutional naming, which makes this a natural fit for a centre, a consortium, or an initiative.
Research organisations tend toward compact names for a practical reason: their full legal names are usually unwieldy, and everyone shortens them anyway. Owning the short form means you control what it is rather than inheriting whatever people invent.
The .org gives a three-character string the institutional read it wouldn’t have on a commercial extension. Same characters, different impression entirely.
Three characters, permanently scarce, and nothing in the market’s structure creates more of them.
Enquiries welcome.