Designation-The designation of a sign refers to the symbol (or collection of symbols) by which some concept is known. The designation of a sign is sometimes referred to as the signifier – that which is signifying something;
Extension – The extension of a sign refers to the range of phenomena that the concept in some way covers. The extension is sometimes known as the referent or the signified – that which is being signified;
Intension – The intension of a sign is the collection of properties that in some ways characterise the phenomena in the extension. The intension is the idea of significance.