array_merge accepts an arbitrary number of arrays as argument. Calling this function once with all the arguments is faster than calling the same function inside a loop, each time with one argument.

Investigating differences between asm2wasm and wasm backend output, one cause of the latter's larger code sizes is that it emits loops over an array differently. For example, in a loop writing array[x ...

Later in the DATA step, when you want to process the variables in the array, you can refer to a variable by either its name or its array reference. For example, the names Reference and books{1} are ...