A path to the paired block forming a begin/end block pair. Both nodes must be in the same network. Nodes wired between the pair are enclosed in a convex hull and are placed inside a code block. Depending on the types of the begin and end blocks, different control flow can be done on the block.

There are two ways to determine which input nodes should be put inside of the code block. If this is not set, they are only enclosed if they depend on the outputs of the paired begin block. If this is set, any node that can be moved into the block is so moved.

It is advantageous with if-blocks to move as many nodes inside as possible as this avoids executing them if the condition is false.

It is advantageous with loop-blocks to move as many nodes outside as possible to avoid having execute them more than once when looping.

By default an output is generated for each input. This allows the specification of extra outputs. If no input wire is present, the value is assumed to be 0 and the type must be specified.

The outputs of an End block are paired with the outputs of the Begin block. If no names are present, the pairing is done in order. If names are present, they are paired by name.