The file formats that support reading channel recordings (ACQ and NTT) cannot be saved back to disk. It was a choice of convenience to create a (more or less) compatible format that can be easily saved (and also is available later without the toolbox).

Whereas most binary formats come with a specific field-by-field description, MAT files are simply loaded and stored in a xff object, with the main addition that for files not prior created with the toolbox, the largest numeric variable will be assigned to the .Data field and all other variables are stored in the .Info sub-struct.

If a MAT file on disk has the following variables:

• channels: 1531891×6 double
• channelnames: 1×6 cell
• channelinfo: 1×6 struct

Reading this file as an xff object will make the data available as:

• .Data - this will be the channels variable
• .Info - this will be a 1×1 struct with fields .channelnames and .channelinfo; additionally there will be a .DataFieldName field in the .Info property giving the variable name in the MAT-file which .Data represents

Upon saving this object, the .Data property will, again, be stored in a variable with the name of .DataFieldName (and the .DataFieldName will be added to the MAT file so as not having to re-detect the data field).