Block Orientation in the Workflow Definition
A block is the elementary structural element of a workflow definition.
A block always contains a consistent arrangement of steps and operators. A block has one start and one end.
When you define a workflow, you always nest blocks in each other or define blocks after each other. A block can never cover an existing block limit.
When you create a new step or change an undefined step, a complete block is always generated. Functions such as delete, cut or paste always affect the whole block too.
In contrast to purely graphically oriented programs for creating workflow definitions, block-oriented modeling in SAP Business Workflow contributes directly to ensuring the consistency and robustness of the workflow definition. It also enables workflow definitions to be implemented faster.

When you create a condition step, a new block is generated.
In addition to the actual step with the condition check, this block also contains the two results of the condition check in the form of outcomes and an undefined step in each of the two possible branches.