Although you can use almost any word as an identifier, syntactic ambiguities can result from using keywords as identifiers in SQL statements. The statement might fail or might not produce the expected results. For a discussion of the syntactic ambiguities that can result from using keywords as identifiers and an explanation of workarounds for these problems, see Potential Ambiguities and Syntax Errors.
Delimited identifiers provide the easiest and safest way to use a keyword as an identifier without syntactic ambiguities. No workarounds are necessary for a keyword as a delimited identifier. For the syntax and usage of delimited identifiers, see Delimited Identifiers. Delimited identifiers require, however, that your code always use single ( ' ) quotes, rather than double ( " ) quotes, to delimit character-string literals.
For the keywords of the implementation of SQL in Dynamic Server, see Appendix A. Reserved Words for IBM Informix Dynamic Server.
The keywords of SQL in Extended Parallel Server are listed in Appendix B. Reserved Words for IBM Informix Extended Parallel Server.