System Analysis & Design: DFD Guidelines

External entities that provide data or input to a system. They represent the origin of information.

External entities that receive data or output from a system. They represent the destination of information.

Represents the transformation or processing of data within a system. Actions performed for specific business reasons.

The movement of data from one element to another in a system.

Represents data entering a process.

The activities that a business performs to achieve its goals.

External entities are outside the system and interact with the system. For example, customers, suppliers, or government agencies.

Data flows are the movement of information from one part of the system to another. For example, a customer order or an invoice.

Processes are the actions that transform data. For example, processing a customer order or generating an invoice.

Data stores are places where data is stored for later use. For example, a customer database or an inventory file.

A visual representation of data movement in a system, showing processes, data flows, data stores, and external entities.

An entity that exists outside the system but interacts with it, providing or receiving data.

A collection of data stored within the system.

A detailed representation of a specific process within a system that breaks down a higher-level process into sub-processes.

The process of breaking down a higher-level process into two or more sub-processes, providing a more detailed view.

Identifying the name and direction of data flowing between sub-processes within a Level-1 DFD, showing how information moves.

Identifying the name and direction of data stores used to store or retrieve data in a Level-1 DFD, showing where information is kept.

The layout of a Level-1 DFD where sources and destinations of data are identified at a higher level, determining the complexity of the DFD and number of processes.

A process of verifying the accuracy and consistency of constructed DFDs to ensure they are error-free and balanced.

Errors related to incorrect syntax, structure, layout, or conventions in a DFD, affecting its readability.

Errors related to the accuracy and consistency of a DFD with respect to actual or planned business processes, ensuring the DFD accurately reflects the real-world system.

Represents the start of a data flow diagram (DFD) and shows the data inputs and outputs of the entire system.

Represents a specific process in more detail, showing its internal subprocesses, data stores, and data flows.

A diagram showing the main processes within a system and their relationships, including data stores that hold information. It provides a more detailed view than a context diagram.

A bank that provides home loans to customers, processing their applications, verifying creditworthiness, and handling loan payments.

The process of determining a customer's financial risk based on their credit history and ability to repay a loan.

The sale of a loan by a lender to another financial institution, transferring the responsibility for loan repayment.

Regular payments made by a borrower to the lender to gradually repay a loan, usually on a monthly basis.