Knowledge is shared. When knowledge is shared and used, it's modified by the folks who use it. This takes us back to knowledge creation. There are three types of repositories of knowledge. They are Structured Repositories, Unstructured Repositories, and People and they form a continuum in terms of searchability.
Structured repositories are databases, expert systems and the like.
They are characterized by their ease of searchability because they have search aids like indexes, keywords, controlled vocabulary and so forth. I n most organizations these include project reports, sales-call notes and other sources. These are searchable by free text means. The two repositories mentioned above are for explicit knowledge, the knowledge that is out there for all to find, see and use. There's also tacit knowledge.