Boxes and Arrows: Ranganathan for IAs An Introduction to the Thought of S.R. Ranganathan for Information Architects:

"The fundamental facets that Ranganathan developed were: Personality, Matter, Energy, Space, and Time. (Amaze your librarian friends by referring to these by the acronym PMEST!)

Personality : what the object is primarily 'about'. This is considered the 'main facet.'
Matter : the material of the object
Energy : the processes or activities that take place in relation to the object
Space : where the object happens or exists
Time : when the object occurs"

I came across this page through
peterme on Context-Aware Computing