Three characters on the .net in the X-for-Y form. O4E reads as optimisation for enterprise, opportunity for everyone, or operations for ecommerce.
Operations for ecommerce is a real and growing software category. Order management, inventory, returns, and fulfilment are the unglamorous machinery behind every online store, and the tooling for them is fragmented and actively being consolidated.
Optimisation for enterprise fits B2B software generally, where the pitch is nearly always about doing the same thing with less.
The 4-as-for construction is what makes a three-letter string worth having. It gives the reader a grammar to hang the letters on, so the name is recalled as a phrase rather than memorised as a code. That difference decides whether a referral gets typed correctly.
Three characters, fixed supply, .net appropriate for a platform business.
Offers considered.