Next is another kind of DEFINE statement. This one defines not a variable, but the first of your buttons:

DEFINE BUTTON BtnFirst 
     LABEL "First" 
     SIZE 15 BY 1.14.

There is a separate DEFINE statement for each different type of object you can have in your application. You can learn all the particular attributes you can set for each kind of object from the ABL Reference, but they are similar in form. The DEFINE statement first names the object (BtnFirst in this case) and then has a list of whatever attributes you want to define for the object and their values. In this case the AppBuilder has defined the button’s LABEL to be First, because this is what you set it to in the design window. The SIZE is a standard size the AppBuilder defaults, which you can change by resizing the button in the design window.

The following three statements are the definitions for the other three buttons in the window.

DEFINE BUTTON BtnLast 
     LABEL "Last" 
     SIZE 15 BY 1.14.

DEFINE BUTTON BtnNext 
     LABEL "Next" 
     SIZE 15 BY 1.14.

DEFINE BUTTON BtnPrev 
     LABEL "Prev" 
     SIZE 15 BY 1.14.