organic polymer the following example illustrates the invention in this case specific fluorescent properties in a specific part of the document are used as an example many banknotes are supplied with a number of highly fluorescent fibres which emit different colours of light these fibres are distributed arbitrarily through the document the local fluorescence of various types of fibres at a predetermined location can be coded and digitally stored in the chip optionally in encrypted form at the time the document is produced i e during the paper manufacturing phase or during the document printing phase in the event of verification the area in question is read again using the coordinates and orientation which are stored in the chip and the results are compared with one another followed by rejection or acceptance the said coordinates and orientation will generally differ for each separate banknote with the result that verification is completely unique for the said document since the arbitrary property and coordinates are unique for that document in this way the chip of each separate banknote contains a unique code which as it were represents a fingerprint of a specific part of the banknote in question the code of the intrinsic property may be stored either in encrypted or nonencrypted form as has already been mentioned above the use of the substrate according to the invention is not limited to banknotes for other uses such as passports and identity documents part of a biometric property of the legal owner can be used.