Note that in some languages, the ordering of the symbols in the digraphs is important, while in others it is not. For instance, in the BASIC shipped with the TRS-80 (Models I - IV), it is legal to express "greater than or equal to" as either ">=" or "=>" but that in C (for instance) the only allowable sequence is ">=".

Also note that the operator for "is equal to" varies from language to language. In BASIC, the symbol "=" may be the relational operator if used in a conditional context (the condition of an IF statement, for instance) or the assignment operator (in a LET statement, for example). Pascal avoids this by defining the symbol ":=" to be the assignment operator and "=" to be the relational operator, while C defines "==" to be the relational operator and "=" to be the assignment operator.

Perl adds somewhat to the confusion, since it defines relational operators for strings as well, and although they are semantically identical to the mathematical relational operators, they're written differently: "lt", "gt", "le", "ge", "eq", "ne", "cmp" for "less than", "greater than", "less than or equal to", "greater than or equal to", "is equal to", "is not equal to", and "compare", respectively.