Oracle inequality operator: ¬=

Here's my best guess as to the derivation and availability of the various inequality operators:

• <> - the original. Used by a number of languages (BASIC, Pascal, etc). Probably available on all platforms.
• != - from C and it's derivatives (C, C++, Java, C#, etc, blah). I expect this is available on all platforms.
• ¬= - This operator is probably only available on IBM mainframes. I know it's not supported on HP-UX as I just tried it. Near and dear to my heart. From the language PL/I (that's capital 'i', not '1', although it represents the Roman numeral "one", and thus the language is "pee ell one". I knew you wanted to know that :-), IBM's bastard stepchild...ahem, I mean "delightful combination" of FORTRAN, Algol, and a touch of COBOL. PL/I was the second high-level computer language I learned and the first one I used in making a living as a software developer. From the Good Old Days, when men were men, women were women, and computers were water-cooled. Isn't that right, Josiah..? (And ten points extra credit for those who can identify where THAT line comes from!)
• ^= - I suspect this is meant to be similar to the preceding "IBM-only" operator, making it an "IBM-ish" operator for use on computers which lack the IBM "¬" (not) character. Probably supported on all platforms.

FWIW I always use <>. Old habits, like old programmers, die hard. :-)

I always use !=. I do not know about the others, but != has always worked for me on windows and linux.