+of data passed through pipes.
+.PP
+The
+.I refer
+preprocessor and associated programs
+expect input from a file of references
+composed of records separated by blank lines.
+A record is a set of lines (fields),
+each containing one kind of information.
+Fields start on a line beginning with a ``%'',
+followed by a key-letter, then a blank,
+and finally the contents of the field,
+and continue until the next line starting with ``%''.
+The output ordering and formatting of fields
+is controlled by the macros specified for
+.I nroff/troff
+(for footnotes and endnotes) or
+.I roffbib
+(for stand-alone bibliographies).
+For a list of the most common key-letters
+and their corresponding fields, see
+.IR addbib (1).
+An example of a
+.I refer
+entry is given below.
+.SH EXAMPLE
+.PP
+.nf
+%A M. E. Lesk
+%T Some Applications of Inverted Indexes on the \s-1UNIX\s0 System
+%B \s-1UNIX\s0 Programmer's Manual
+%V 2b
+%I Bell Laboratories
+%C Murray Hill, NJ
+%D 1978
+.fi