The object has at least two components, which relate to each other (in
  the sense of a relational database).  info holds information
  about the individual samples, and data holds information about
  individual peaks (many of which may belong to a single sample).
Column definitions:
- info:
 - 
      - knowns.pk:
- Unique positive integer, used to identify
	individual knowns (i.e. a “primary key”). 
- species:
- Character, giving species name. 
 
- data:
 - 
      - knowns.fk:
- Positive integer, indicating which sample
	the peak belongs to (by matching against - info$knowns.pk)
	(i.e. a “foreign key”).
 
- primer:
- Character, giving the name of the primer
	used. 
- enzyme:
- Character, giving the name of the
	restriction digest enzyme used. 
- size:
- Numeric, giving size (in base pairs) of the
	peak. 
 
In addition, TRAMPknowns will create additional columns holding
  clustering information (see group.knowns).  Additional
  columns are allowed (and retained, but ignored) in both data.frames.
  Additional objects are allowed as part of the TRAMPknowns
  object, but these will not be written by
  write.TRAMPknowns; any extra objects passed (via
  ...) will be included in the final TRAMPknowns object.
The cluster.pars argument controls how knowns will be clustered
  (this will happen automatically as needed).  Elements of the list
  cluster.pars may be any of the three arguments to
  group.knowns, and will be used as defaults in
  subsequent calls to group.knowns.  If not provided, default
  values are: dist.method="maximum",
  hclust.method="complete", cut.height=2.5 (if only some
  elements of cluster.pars are provided, the remaining elements
  default to the values above).  To change values of clustering
  parameters in an existing TRAMPknowns object, use
  group.knowns.
A known contains at most one peak per enzyme/primer combination.
  Where a species is known to have multiple TRFLP profiles, these should
  be treated as separate knowns with different, unique, knowns.pk
  values, but with identical species values.  A sample containing
  either pattern will then be recorded as having that species present
  (see group.knowns).