Files

``Everything is a file", so let's start explaining the idea by a clear designation of the involved types of files:

1. definition of the XML Schema, formally defining the syntax of the language, is contained in the file http://eeg.pl/SignalML.xsd.

2. metainformation files should be unique for each existing format (or its version), so they should be possibly identified by a URL, e.g. for the European Data Format it is http://eeg.pl/meta_EDF.xml (Table 1)

3. annotation files are related uniquely to a given data file, and contain:
   • complete information necessary for a proper interpretation of the data in a given file. Reference to a proper metainformation file may be sufficient, or, alternatively, explicit values of parameters (sampling, number_of_channels etc.) defined in section 2.2 can be included,
   • filename and control sum identifying uniquely the data file to which the annotations relate,
   • montage (transform) applied to the signal when creating annotations,
   • definitions of tags/annotations,
   • tags/annotations based upon the above definitions.

As a special case, annotation files with a complete set of parameters describing a ``raw" (containing only data samples) datafile may constitute an autonomous format--this particular case would partially correspond to the translation proposed in [4]. Content of an example annotation file is given in Table 2.