string-part _ string-part
_ character is used to concatenate two or more string parts into a single string. Note that the maximum length of an OmniMark string is 2,048 characters, excluding the surrounding quotation marks and any underscores used to enter long strings.
_ character must be used when joining quoted SGML or XML names. It is also useful when a string exceeds a single line in length.
Unlike the underscore keyword, the
|| keyword is a run-time concatenator allowing returned values, rather than only strings, to be joined. This makes the
|| keyword more flexible than the underscore, so the underscore should be used only in the cases noted above.