demonstrates, how you might print out the heading of a contents page on page 1 of a book (if that book was displayed using ZX Spectrum Next characters of course!) Try running this: ``` 10 FOR n=0 TO 20 20 PRINT TAB 8*n;n; 30 NEXT n ``` This shows what is meant by the **TAB** numbers being reduced *modulo X*. For a more elegant example, change the **8** in line 20 to a **6** or even try to implement this on a different *layer* such as the *HiRes* one as it allows more room for demonstration of this functionality by adding **LAYER 1,2** before line 10. As you'll see in *Chapter 20*, **TAB** accepts a two-byte parameter which means it accepts a maximum column number of **65535**! Not that you'd ever want to use that! Some small points: 1. These new items are best terminated with semicolons, as we have done above. You can use commas (or nothing, at the end of the statement), but this means that after having carefully set up the **PRINT** position, you immediately move it on again which wouldn't usually be terribly useful. 2. As a reminder, you cannot print on the bottom two rows (22 and 23) on the *Layer 0* screen because they are reserved for commands, **INPUT** data (see below), reports/errors and so on. References to the *bottom line* usually mean line 21 and only apply to *Layer 0*. 3. You can use **AT** to put the **PRINT** position even where there is already something printed; the old stuff will be obliterated when you print more. ### CLS Another statement that's connected with **PRINT** (although it's not *only* limited to it), is **CLS**. This clears the *whole screen*, something that is also done by **CLEAR** and **RUN**. The **LAYER** command does not clear the screen however, although it may switch to a new screen that has nothing on it. *Do not* assume a *Layer* is free of stuff just because you haven't used a command that outputs something on screen. Always give **CLS** after switching *layers* if you want to ensure a screen free of anything on it. ### Scrolling When the printing reaches the bottom of the screen, the latter moves its contents upwards, to clear room on the bottom for new content. You can see this if you go into the status area by using the *Edit menu* option *Screen* and then type: ``` CLS:FOR n=1 TO 22:PRINT n:NEXT n ``` and then do: ``` PRINT 99 ``` a few times. Depending on the *layer* you are on, the computer may pause its screen output for you to review the content being printed and ask you a question or may simply display a block cursor at the lower right corner and wait. On *Layer 0*, if the computer is printing out reams and reams of stuff on screen, it asks you before continuing. You can see this happening if you type: ``` CLS:FOR n=1 TO 100:PRINT n:NEXT n ```