This pseudo field contains the old reference key --- before generating a new
one. If none has been given then the access fails.
$sortkey
This pseudo field contains the string according to which the sorting is
performed. It defaults to the reference key.
$default.key
This pseudo field contains the value of the resource default.key
similarly the resources fmt.name.title, fmt.title.title,
fmt.name.name, fmt.inter.name, fmt.name.pre, and
fmt.et.al can be accessed.
$source
This pseudo field contains the name of the file the entry has been read
from. If this file can not be determined, e.g. because the entry has been
read from stdin, then this pseudo field is empty.
$type
This pseudo field contains the type of the entry, i.e. the string following
the initial @ of an BibTeX entry. E.g. article. It is
always present.
@type
This pseudo field is matched against the type of the entry. If they are
identical (ignoring cases) then the type is returned. Otherwise the access
fails.
In an article item the specification %s(@Article) succeeds and
returns Article whereas %s(@Book) fails.
$day
This pseudo field contains the current day as a two digit number or the
empty string if this value is not available. The date and time values are
determined at the beginning of the BibTool run and does not reflect the
execution time used by BibTool.
On some systems the timing function might be missing or returning strange
values. In this case the timing fields simply return the empty string.
$month
This pseudo field contains the current month as a two digit number or the
empty string if this value is not available.
$mon
This pseudo field contains the current month name as a string or the
empty string if this value is not available.
$year
This pseudo field contains the current year as a four digit number or the
empty string if this value is not available.
$hour
This pseudo field contains the current hour as a two digit number or the
empty string if this value is not available.
$minute
This pseudo field contains the current minute as a two digit number or the
empty string if this value is not available.
$second
This pseudo field contains the current second as a two digit number or the
empty string if this value is not available.
$user
This pseudo field contains the contents of the environment variable
$USER or the empty string if this value is not available. On UN*X
systems this variable usually contains the name of the user. This can be
used to write logging information into a field.
$hostname
This pseudo field contains the contents of the environment variable
$HOSTNAME or the empty string if this value is not available.
Reference Manual