A schema that represents the structure of business transactions used by clients in the real world. It is considered to be unnormalized data.

The dictionary defines the word "schema" as a plan, diagram, scheme or an underlying organizational structure.  It can also mean a conceptual framework.

 
Running a business is a not a simple undertaking.  In fact, it can get very complex as the business grows and growth is one of the priority goals of any business. 

For a business to be efficiently managed, it has to have an adopted standard of rules and policies.  It has to have business semantics detailed in declarative description.

Business rule is very important to define a business schema.  The business rule can influence and guide behaviors and result to support to policies and response to environmental events and situations.  Rules may be the top means whereby a business organization directs its movement and defines it objectives and perform appropriate actions.

A business schema can be represented in a data model with un-normalized data.  A data model can reflect two and a half of the four different kinds of business rules which are terms, facts, results of derivations and constraints.  A data model can reflect the data parameters that control the rules of the business.

The terms in a business schema is the precise definition of words used in the business rule.  Order, Product Type and Line items are terms that refer to entity class which are things of heavy significance to the business.  Attributes are terms that describe the entity class.  For example, total number and total value are attributes of an order.  Attributes of Product Type may include manufacturer, unit price and materials used.  Quantity and extended value are attributes for Line Item entity class.  

Facts, another business rule in the schema, describe a thing like the role a thing plays and other descriptions.  A data model has three kinds of facts which relationships, attributes and super types / sub-types.

Derivation can be any attribute that is a derivative of other attributes or system variables.  For example, the extended value attribute for the entity class line items can be determined by multiplying quantity of line item by the unit price of the product type.

Constraints refer to conditions which determine what values a relationship or an attribute can or cannot have.

Many companies hire consultants to document and consolidated the standards, rules, policies and practices.  Then these documentations are handed to IT and database consultants so that they can be transformed into database rules that follow the business schema.

Many independent or third party consultancy firms, research institutions and software application vendors and developers offer rich business schema solutions.  Even if business rules are constantly changing and software applications are already in final form, these software applications can be customized to be in sync with the constantly changing business rules in particular and the schema in general.

A business rules engine is widely used software application that is used to manage and automate business rules to follow legal regulations. For example the law that states "An employee can be fired for any reason or no reason but not for an illegal reason" is ensured to be followed by the software. 

The rule engine’s most significant function is to help classify, register and manage business and legal rules and verify for constancy.  Likewise, the can infer some rules basing other existing rules and relate them to IT application.  Rules in IT applications can automatically detect unusual situations arising from the operations. 

With a business schema clearly defined, there is little room for mistake in running a business successfully.