The guess_udic functions guess a universal dictionary from the
data present, for some NMR data formats not all the information can
be determined from the data presented. In the case of Bruker data
only the size parameter is set, the other values are set to default
values that should be changed by the user. This limited information
in the universal dictionaries created from Bruker data is a result
of 1) Me only having had a limited need to work with Bruker data
(most the spectrometer I worked on were Varian/Agilent) and 2) The
necessary metadata (carrier frequency, offset, spectral width) seems
to be stored in the various acqus files in non-regular positions.
From my experience even NMRPipe's bruker command does not
reliability determine these parameters, rather users must choose
them from a list of possible choices.
There are two nmrglue forks ,  and a open issue  which
try to determine more of these spectral parameters from the metadata
parsed from the acqus files but neither branch seems to get all the
parameters correct. If anyone would like to work on improving this
I would welcome a pull request. For the time being universal
dictionaries created using nmrglue.bruker.guess_udic must be
corrected by hand.
- Jonathan Helmus