The methodological stratum of the General Theory of Information (GTI) studies basic principles of information theory and information technology.

Ontological Principle O1

(the Locality Principle). It is necessary to separate information in general from information (or a portion of information) for a system R. 

In other words, empirically, it is possible to speak only about information (or a portion of information) for a system. This principle separates local and global approaches to information definition, i.e., in what context information is defined.

The Locality Principle explicates an important property of information, but says nothing what information is. The essence of information is described by the second ontological principle, which has several forms. 

Ontological Principle O2 

(the General Transformation Principle). In a broad sense, information for a system R is a capacity to cause changes in the system R. 

Thus, we may understand information in a broad sense as a capacity (ability or potency) of things, both material and abstract, to change other things. Information exists in the form of portions of information. 

Information in a proper sense is defined of structural infological systems. In essence, any subsystem of a system may be considered as its infological system. However, information in a strict sense acts on structural infological systems where an infological system is structural if all its elements are structures. For example, systems of knowledge are structures.

Ontological Principle O2g 

(the Relativized Transformation Principle). Information for a system R relative to the infological system IF(R) is a capacity to cause changes in the system IF(R). 

Elements from IF(R) are called infological elements. 

Ontological Principle O2a 

(the Special Transformation Principle). Information in the strict sense or proper information or, simply, information for a system R, is a capacity to change structural infological elements from an infological system IF(R) of the system R.  

An infological system IF(R) of the system R is called cognitive if IF(R) contains (stores) elements or constituents of cognition, such as knowledge, data, ideas, fantasies, abstractions, beliefs, etc. A cognitive infological system of a system R is denoted by CIF(R) and is related to cognitive information. 

Ontological Principle O2c 

(the Cognitive Transformation Principle).  Cognitive information for a system R, is a capacity to cause changes in the cognitive infological system IFC(R) of the system R.  

Ontological Principle O3 

(the Embodiment Principle). For any portion of information I, there is always a carrier C of this portion of information for a system R. 

The substance C that is a carrier of the portion of information I is called the physical, or material, carrier ofI.

Ontological Principle O4

(the Representability Principle). For any portion of information I, there is always a representation C of this portion of information for a system R.

Ontological Principle O5

(the Interaction Principle). A transaction/transition/transmission of information goes on only in some interaction of C with R. 

Ontological Principle O6

(the Actuality Principle).  A system R accepts a portion of information I only if the transaction/transition/transmission causes corresponding transformations in R.

Ontological Principle O7

(the Multiplicity Principle). One and the same carrier C can contain different portions of information for one and the same system R.