Re: [Groff] refer "label" question

[joerg van den hoff]

hi all,

I'm trying to come to terms with the fine-tuning of 'refer' output.

the problem is as follows:
I have attached a text file "tt" and a 2-entry refer database "tt.db". 
the aim is to get labels in the text consisting of the first three 
authors plus "et al". I don't understand how to achieve this at all.
what seems to be feasible with 'refer' is to enforce use of the 
unambiguous initial subsequence of authors + "et al" (which usually will
be only the first author).

but even this seems not to work correctly:


the refer manpage says:

======================cut================================
et-al* string m n
==================
Control use of et al in the  evaluation  of  @
expressions in label expressions.  If the num-
ber of  authors  needed  to  make  the  author
sequence unambiguous is u and the total number
of authors is t then the last t-u authors will
be replaced by string provided that t-u is not
less than m and t is not  less  than  n.   The
default behaviour is

et-al " et al" 2 3
========================cut==============================


for the two entries in 'tt.db' the parameters "t" and "u" mentioned in 
the manpage are

#one
t = 1
u =1

#two:
t = 9
u = 2

if I understand the manpage correctly, the standard setting of "et-al"
should result, in this example, in labels
"Carson, 2003" and "Carson, Cunningham et al, 2003", but this is not 
what happens: the second label is shortened to  "Carson et al, 2003" in 
this case.

therefore, in the attached example, I believe the first variant is OK, 
the second is not. am I making a mistake or is this broken?

maybe I miss some important point: the 'refer' manpage states in the 
"label" section concerning the "@" tag:

========================cut==============================
@
===
All the authors joined as specified by the join-authors command.
The  whole  of each author's name will be used.  However, if the
references are sorted by author (that is the sort  specification
starts  with A+), then authors' last names will be used instead,
provided that this does not introduce  ambiguity,  and  also  an
initial  subsequence  of  the authors may be used instead of all
the authors, again provided that this does not introduce ambigu-
ity.   The use of only the last name for the i-th author of some
reference is considered to be ambiguous if there is  some  other
reference, such that the first i-1 authors of the references are
the same, the i-th authors  are  not  the  same,  but  the  i-th
authors'  last names are the same.  A proper initial subsequence
of the sequence of authors for some reference is  considered  to
be ambiguous if there is a reference with some other sequence of
authors which also has that subsequence as a proper initial sub-
sequence.   When  an initial subsequence of authors is used, the
remaining authors are replaced by the string  specified  by  the
et-al command; this command may also specify additional require-
ments that must be met before  an  initial  subsequence  can  be
used.   @ tentatively evaluates to a canonical representation of
the authors, such that authors that compare equally for  sorting
purpose will have the same representation.
========================cut==============================
question: _how_ can I use/create subsequences of authors?

sorry for not being able to make this shorter.


regards
joerg

.R1
no-default-database
search-truncate 255
move-punctuation
database tt.db
search-ignore AE
bracket-label " (" ")" "; "
no-abbreviate-label-ranges
sort-adjacent-labels
sort A+
label @',\~'D.y%a*
.R2
.\"-------------------------------------------------------------------------------
.\"this should output all the authors in the label:
.R1
et-al " et al" 9 3
.R2
A TEST IS A TEST IS A TEST.
.[
Carson2003
.]
.[
Carson2003a
.]
.\"-------------------------------------------------------------------------------
.\" the default setting:
.R1
et-al " et al" 2 3
.R2
.\"-------------------------------------------------------------------------------

\l'5i'

a test is a test is a test.
.[
Carson2003
.]
.[
Carson2003a
.]

%T PET Pharmacokinetic Course 
%B PET Pharmacokinetic Course Manual
%A RE Carson
%A V Cunningham
%A RN Gunn
%A J van\~den\~Hoff
%A GM Knudsen
%A AA Lammertsma
%A KL Leenders
%A RP Maguire
%A W Müller-Schauenburg
%E RP Maguire
%E KL Leenders
%I University of Groningen, Groningen, The Netherlands and McGill University, 
Canada
%C Montreal
%D 2003
%O 
%L Carson2003

%T Tracer Kinetic Modeling in PET
%A RE Carson
%B Positron Emission Tomography
%E PE Valk
%E DL Bailey
%E DW Townsend
%E MN Maisey
%I Springer 
%C London
%D 2003
%P 147-79
%O ISBN 1852334851
%K BOOK
%L Carson2003a