+@subsubheading PIBHEX and RBHEX Formats
+
+These are hexadecimal formats, for reading and writing binary formats
+where each byte has been recoded as a pair of hexadecimal digits.
+
+A hexadecimal field consists solely of hexadecimal digits
+@samp{0}@dots{}@samp{9} and @samp{A}@dots{}@samp{F}. Uppercase and
+lowercase are accepted on input; output is in uppercase.
+
+Other than the hexadecimal representation, these formats are equivalent
+to PIB and RB formats, respectively. However, bytes in PIBHEX format
+are always ordered with the most-significant byte first (big-endian
+order), regardless of the host machine's native byte order or @pspp{}
+settings.
+
+Field widths must be even and between 2 and 16. RBHEX format allows no
+decimal places; PIBHEX allows as many decimal places as a PIB format
+with half the given width.
+
+@node Time and Date Formats
+@subsubsection Time and Date Formats
+
+@cindex time formats
+@cindex date formats
+In @pspp{}, a @dfn{time} is an interval. The time formats translate
+between human-friendly descriptions of time intervals and @pspp{}'s
+internal representation of time intervals, which is simply the number of
+seconds in the interval. @pspp{} has three time formats:
+
+@float
+@multitable {Time Format} {@code{dd-mmm-yyyy HH:MM:SS.ss}} {@code{01-OCT-1978 01:31:17.01}}
+@headitem Time Format @tab Template @tab Example
+@item MTIME @tab @code{MM:SS.ss} @tab @code{91:17.01}
+@item TIME @tab @code{hh:MM:SS.ss} @tab @code{01:31:17.01}
+@item DTIME @tab @code{DD HH:MM:SS.ss} @tab @code{00 04:31:17.01}
+@end multitable
+@end float
+
+A @dfn{date} is a moment in the past or the future. Internally, @pspp{}
+represents a date as the number of seconds since the @dfn{epoch},
+midnight, Oct. 14, 1582. The date formats translate between
+human-readable dates and @pspp{}'s numeric representation of dates and
+times. @pspp{} has several date formats:
+
+@float
+@multitable {Date Format} {@code{dd-mmm-yyyy HH:MM:SS.ss}} {@code{01-OCT-1978 04:31:17.01}}
+@headitem Date Format @tab Template @tab Example
+@item DATE @tab @code{dd-mmm-yyyy} @tab @code{01-OCT-1978}
+@item ADATE @tab @code{mm/dd/yyyy} @tab @code{10/01/1978}
+@item EDATE @tab @code{dd.mm.yyyy} @tab @code{01.10.1978}
+@item JDATE @tab @code{yyyyjjj} @tab @code{1978274}
+@item SDATE @tab @code{yyyy/mm/dd} @tab @code{1978/10/01}
+@item QYR @tab @code{q Q yyyy} @tab @code{3 Q 1978}
+@item MOYR @tab @code{mmm yyyy} @tab @code{OCT 1978}
+@item WKYR @tab @code{ww WK yyyy} @tab @code{40 WK 1978}
+@item DATETIME @tab @code{dd-mmm-yyyy HH:MM:SS.ss} @tab @code{01-OCT-1978 04:31:17.01}
+@item YMDHMS @tab @code{yyyy-mm-dd HH:MM:SS.ss} @tab @code{1978-01-OCT 04:31:17.01}
+@end multitable
+@end float
+
+The templates in the preceding tables describe how the time and date
+formats are input and output:
+
+@table @code
+@item dd
+Day of month, from 1 to 31. Always output as two digits.
+
+@item mm
+@itemx mmm
+Month. In output, @code{mm} is output as two digits, @code{mmm} as the
+first three letters of an English month name (January, February,
+@dots{}). In input, both of these formats, plus Roman numerals, are
+accepted.
+
+@item yyyy
+Year. In output, DATETIME and YMDHMS always produce 4-digit years;
+other formats can produce a 2- or 4-digit year. The century assumed
+for 2-digit years depends on the EPOCH setting (@pxref{SET EPOCH}).
+In output, a year outside the epoch causes the whole field to be
+filled with asterisks (@samp{*}).
+
+@item jjj
+Day of year (Julian day), from 1 to 366. This is exactly three digits
+giving the count of days from the start of the year. January 1 is
+considered day 1.
+
+@item q
+Quarter of year, from 1 to 4. Quarters start on January 1, April 1,
+July 1, and October 1.
+
+@item ww
+Week of year, from 1 to 53. Output as exactly two digits. January 1 is
+the first day of week 1.
+
+@item DD
+Count of days, which may be positive or negative. Output as at least
+two digits.
+
+@item hh
+Count of hours, which may be positive or negative. Output as at least
+two digits.
+
+@item HH
+Hour of day, from 0 to 23. Output as exactly two digits.
+
+@item MM
+In MTIME, count of minutes, which may be positive or negative. Output
+as at least two digits.
+
+In other formats, minute of hour, from 0 to 59. Output as exactly two
+digits.
+
+@item SS.ss
+Seconds within minute, from 0 to 59. The integer part is output as
+exactly two digits. On output, seconds and fractional seconds may or
+may not be included, depending on field width and decimal places. On
+input, seconds and fractional seconds are optional. The DECIMAL setting
+controls the character accepted and displayed as the decimal point
+(@pxref{SET DECIMAL}).
+@end table