Strings can be divided into separate, quote-delimited parts that are joined with an underscore character
(_). There are no restrictions on the use of white space around the string parts or the underscore.
This convention is especially useful for entering long strings that don't fit on a single line within a program or
for entering strings that contain both single and double quotation marks.
You can also use the || concatenation operator. This operator can be applied to any two
string, string source, or markup source expressions, while the underscore
works only on string literals.
The maximum length of an OmniMark string, excluding enclosing quotation marks and any underscores used to enter long strings, is 2,048 characters.