empty values for ?Text (answer to #1414)
rd at sanger.ac.uk
Fri Oct 10 04:48:10 EST 1997
Dave Matthews says he used to use "" or " " for ?Text where he wanted
to skip an item in a multiple-item field, as in
> Probe : "xyz"
> Wheat_polymorphism "" HindIII "0.0 (1,13)"
We made this illegal in 4_5. This was necessary because all items in
a class must have a unique name, and the 0th item with an implicit
empty name was already used for storing the model. (Remember that
?Text is a handled as a class just like ?Probe). It turns out that
using "" gave spurious references to the models, and even allowed
people to edit the models in alarming ways. This was definitely a
I suggest that you use some symbol such as "-" as a convention for
You can still have empty Text, as opposed to ?Text.
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