You can allocate and initialise memory for data using data definition directives. There are a wide range of data definition directives covering a wide range of uses, and many of these have the same semantics.

You can define typed variables using the DV directive. The DS directive reserves storage but does not initialize variables.

Data alignment is critical in many instances. Defining exactly how your data are arranged in memory is usually a requirement of interfacing with the outside world using devices or communication areas shared between the application and operating system. You can align the current section's location counter with the ALIGN and EVEN directives.