Any printable character specified appears in the heading, including spaces. Double-byte data can be used when the DBCS assembler option is specified. The double-byte data must be valid. Variable symbols are allowed. However, the following rules apply to ampersands and apostrophes:

• The DBCS ampersand and apostrophe are not recognized as delimiters.
• A double-byte character that contains the value of an EBCDIC ampersand or apostrophe in either byte is not recognized as a delimiter when enclosed by SO and SI.
• A single ampersand initiates an attempt to identify a variable symbol and to substitute its current value.
• A pair of ampersands is printed as one ampersand.
• A pair of apostrophes is printed as one apostrophe.
• An unpaired apostrophe followed by one or more spaces ends the string of characters printed. If a non-space character follows an unpaired apostrophe, the assembler issues an error message and prints no heading.

Only the characters printed in the heading count toward the maximum of 100 characters allowed. If the count of characters to be printed exceeds 100, the heading that is printed is truncated and error diagnostic message

ASMA062E Illegal operand format

is issued.