You're reading the documentation for an older, but still supported version (1.33.4).
For information on the latest version, please have a look at 1.33.5.

2.2.8 I/O & Modbus & Communication

I/O

• GPIO_CTRLBOX_DIGITAL_INDEX
• GPIO_CTRLBOX_ANALOG_INDEX
• GPIO_TOOL_DIGITAL_INDEX
• GPIO_TOOL_ANALOG_INDEX
• GPIO_ANALOG_TYPE
• OUTPUT_TYPE

Communication

• BYTE_SIZE
• STOP_BITS
• PARITY_CHECK
• ENCORDER_POLARITY

Modbus

• MODBUS_REGISTER_TYPE