The date of establishment or date of founding of an institution is the date on which that institution chooses to claim as its starting point. Often the criteria that define a date of establishment or founding are ill-defined--or more specifically, are ill-defined in general, although each institution tends to adopt a rather rigid definition of its own date of establishment.
Other definitions of establishment are also possible.
A university may define its date of establishment as:
Other definitions of the date on which a university was established are also possible, as considered reasonable by the university's governing body or executive officers.
Ultimately an established date of an institution either is decided upon as an internal matter by that institution or is decided for that institution by a normative higher authority outside that institution. For all institutions falling into a particular type of similar institutions, if the date of establishment is not decided by the same authority using the same criteria variations in the definition of the date of establishment can arise.