If you know how big your inventory is going to be, you can use:
Buff(<size>)->varWhere you insert the size and the variable. To access it use {var} and ->{var} to write. Add an ^r after it if you want to change a 2 byte value.
As for text based, that has nothing to do with the inventory system.

What the code you mentioned is doing is taking the os variable named Str00 and copy-pasting its contents as data into the end of the program. He had meaningful data in Str00 but since you don't have any data to include, you don't need to use those statements.