Blurb::
String (categorical) valued point histogram variable

Description::
This probability mass function is string-valued; the abscissa values
must all be strings.  The \c n abscissa values are paired with \c n \c
counts which indicate the relative frequency (mass) of each string
relative to the other specified strings.

Topics::	

Examples::
\verbatim
histogram_point_uncertain
  string = 2
  pairs_per_variable = 2            3 
  abscissas          = 'no' 'yes'   'function1' 'function2' 'function3'
  counts             = 1     1      1           2           1
  descriptors        = 'vote'       'which_function'
\endverbatim

Here there are two variables, the first one ('vote') has two possible
string values 'yes' and 'no' which are equally probable.  The second
one has three options for 'which_function', and 'function2' is twice
as probable as 'function1' or 'function3'.

Theory::
Faq::
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