It's not really an abbreviation in the sense you mean; it's two words combined to make a new name. In that sense, it just becomes a proper noun. The thing with "forex" is that it actually refers to "foreign exchange", and is thus an abbreviation, whereas "Pasmo" is simply the name of something (and the etymology is not crucial to its function as such).

And even if you insist that it's an abbreviation, there's still no reason for it to appear in all-caps. The forex page on Wikipedia doesn't even use all-caps for "forex," so that kind of dumps your argument (not to be rude, but this is the case: http://en.wikipedia.org/wiki/Forex).

Also note that EBay, when refering to itself (on its website and in reports, etc.), starts sentences with "eBay," but the Wall Street Journal quite rightly follows convention and begins such sentences with "EBay."

I find the trend of using all-caps when there is no basis for doing so highly annoying. It also, quite simply, goes against well-established rules of style. *Regardless* of what style the company forces its English translators and copywriters to follow (probably against their will) for the corporate website and materials, Wikipedia is free to follow normal English conventions. Wikipedia does not have to support the company's misguided use of SHOUTING (which is (and this is an unverifiable statement based on experience) probably due to a lack of understanding of English style conventions—or a refusal to accept them, even after they have been explained—rather than due to an informed decision based on whether the name constitutes an acronym/abbreviation or not). The name should appear as "Pasmo."