Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help ft_datatype_comp”.

  FT_DATATYPE_COMP describes the FieldTrip MATLAB structure for comp data
 
  The comp data structure represents time-series channel-level data that has
  been decomposed or unmixed from the channel level into its components or
  "blind sources", for example using ICA (independent component analysis) or
  PCA. This data structure is usually generated with the FT_COMPONENTANALYSIS
  function.
 
  An example of a decomposed raw data structure with 100 components that resulted from
  a 151-channel MEG recording is shown here:
 
            topo: [151x100 double]  the compoment topographies
        unmixing: [100x151 double]  the compoment unmixing matrix
       topolabel: {151x1 cell}      the channel labels (e.g. 'MRC13')
           label: {100x1 cell}      the component labels (e.g. 'runica001')
            time: {1x10 cell}       the time axis [1*Ntime double] per trial
           trial: {1x10 cell}       the numeric data [151*Ntime double] per trial
            grad: [1x1 struct]      information about the sensor array (for EEG it is called elec)
             cfg: [1x1 struct]      the configuration used by the function that generated this data structure
 
  The only difference to the raw data structure is that the comp structure contains
  the additional fields unmixing, topo and topolabel. Besides representing the time
  series information as a raw data structure (see FT_DATATYPE_RAW), it is also
  possible for time series information to be represented as timelock or freq
  structures (see FT_DATATYPE_TIMELOCK or FT_DATATYPE_FREQ).
 
  Required fields:
    - unmixing, topo, topolabel
 
  Optional fields:
    - cfg, all fields from FT_DATATYPE_RAW, FT_DATATYPE_TIMELOCK or FT_DATATYPE_FREQ
 
  Historical fields:
    - offset, fsample
 
  Revision history:
  (2014) The combination of comp with raw, timelock or freq has been defined explicitly.
 
  (2011) The unmixing matrix has been added to the component data structure.
 
  (2003) The initial version was defined
 
  See also FT_DATATYPE, FT_DATATYPE_COMP, FT_DATATYPE_DIP, FT_DATATYPE_FREQ,
  FT_DATATYPE_MVAR, FT_DATATYPE_RAW, FT_DATATYPE_SOURCE, FT_DATATYPE_SPIKE,
  FT_DATATYPE_TIMELOCK, FT_DATATYPE_VOLUME