In addition to narrative text, the following line formats may be used:
Conditional (C2)
This field specifies any queries related to the collection referred to in the message.
For frequently used query texts, the following predefined query numbers may be used:
When a message contains more than one query, each query must appear on a separate line.
Queries must appear in ascending order.
When Supplement 2 is used, ie, two different pieces of supplementary information are provided, it must be preceded by a slash "/".
Narrative text must not begin with a slash and, if used, must begin on a new line and be the last information in the field.