Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help fieldtrip2spss”.

  FIELDTRIP2SPSS compiles data and correpsonding labels into a textfile,
  suitable for importing into SPSS or JASP (
  Use as
    fieldtrip2spss(filename, labels, data)
  When exporting from MATLAB, set:
    - filename; should be string (e.g. 'counts.txt')
    - labels; should be a cell array (e.g. {'ones', 'twos', 'threes'})
    - data; should be either a vector or matrix (e.g. [1 2 3; 1 2 3; 1 2 3])
  When importing to SPSS, set;
    - variables included at top of file: 'yes'
    - first case of data on line number: '2' (default)
    - delimiter appearing between variables: 'tab' (default)
  In case the columns that make up the data matrix have unequal lengths
  (e.g. because of different number of subjects per group), use:
    data         = ones(30,2)*9999
    data(1:30,1) = 1 (30 subj in Group 1)
    data(1:20,2) = 2 (20 subj in Group 2)
  After importing to SPSS, click the Missing cell in the Variable View
  window and enter 9999 as the missing value definition.