Various data classification models are available for different environments. Some security
models focus on the confidentiality of the data (such as Bell-La Padula) and use different
classifications. For example, the U.S. military uses a model that goes from most confidential
(Top Secret) to least confidential (Unclassified) to classify the data on any given system. On
the other hand, most corporate entities prefer a model whereby they classify data by business unit (HR, Marketing, R&D, etc.) or use terms such as Company Confidential to define items
that should not be shared with the public. Other security models focus on the integrity of the
data (for example, Bipa); yet others are expressed by mapping security policies to data
classification (for example, Clark-Wilson). In every case there are areas that require special
attention and clarification.