Short Answer: Requirements!  ;-)

Seriously... The reality is that there isn't such as thing as a standard requirements document template to help guide the business analyst in the creation of this document.

The format of a Requirements Document vary depending on the type and size of project, type of organization, maturity of the business analysis team, use of specialized requirements management tools, type of methodology and development process(agile vs. RUP vs. structured analysis), etc.

Having said that, here are some common types of information found in many requirements documents:

• Background/History
• Scope and Objectives
• Regulatory Requirements
• Business Level Requirements
  • Strategic
  • Tactical (Interoperability)
  • Operational (Process related mostly)
• Stakeholder and User Analysis
• User Requirements (the abilities that the users need)
• Functional Requirements
• Non-functional Level User Requirements
• Assumptions/Constraints
• Risks and Dependencies
• Solution Options
• Business Glossary (the nouns and noun-verb phrases of the business)
• Reference to Business Rules
• Reference to Business Case/Vision
• Use Case Models

One more observation: requirements documents are also known by a variety of names which, at times, mean the same thing and, other times, refer to totally different documents:

• Requirements Document
• Business Requirements Document (BRD)
• Software Requirements Document
• Software Requirements Specification (SRS)