The result is a character matrix containing the names of all tied files, with one file name per row.  The number of columns is that required by the longest file name. 

A file name is returned precisely as it was specified when the file was tied, except that the directory delimiter \ is replaced by /.  If no files are tied, the result is a character matrix with 0 rows and 0 columns.  The rows of the result are in the order in which the files were tied.

      '/usr/pete/SALESFILE' ⎕FSTIE 16
 
      '..\budget\COSTFILE' ⎕FSTIE 2
 
      'PROFIT' ⎕FCREATE 5
 
       ⎕FNAMES
/usr/pete/SALESFILE
../budget/COSTFILE
PROFIT
 
      ⍴⎕FNAMES
3 19
      ⎕FNUMS,⎕FNAMES
16 /usr/pete/SALESFILE
 2 ../budget/COSTFILE
 5 PROFIT