data -- introduces a list of data-items

 
data 9,"world" 
... 
read b,a$ 

The data-keyword introduces a list of comma-seperated list of strings or numbers, which may be retrieved with the read-command.
The data-command itself does nothing; it just stores data. A single data-command may precede an arbitrarily long list of values, in which strings or numbers may be mixed at will.

yab internally uses a data-pointer to keep track of the current location within the data-list; this pointer may be reset with the restore-command.

do 
	restore 
	for a=1 to 4 
		read num$,num 
		print num$,"=",num 
	next a 
loop 
data "eleven",11,"twelve",12,"thirteen",13,"fourteen",14 

This example just prints a series of lines eleven=11 up to fourteen=14 and so on without end.
The restore-command ensures that the list of data-items is read from the start with every iteration.