returning 0 if there is no number in the string.

VLIN y1,y2 AT x
Draws a vertical line on the lores screen from x,y1 to x,y2 in the
currently set COLOR. y1 and y2 do not need to be in sorted order. If
the lores screen is not active, garbage may appear on the text screen.
x, y1, and y2 should be within the limits of the lores graphics screen
(0..39 for x, 0..47 for y), or the results may be unpredictable.

VTAB val Sets the cursor's vertical position on the screen. 1 is the
top row on the screen, 24 is the bottom.

WAIT memaddr,val1[,val2]
Goes into an uninterruptable loop (except by control-Reset) looking at
a memory address. The contents of memaddr are bitwise AND'd with val1,
and compared to val2 (or 0 as a default). If the two are identical,
then it keeps looping, else it exits.

XDRAW shapehum [AT x,y]
Erases the hires shape specified in the current HCOLOR, SCALE and ROT
on the current hires screen. (Technically, it draws in an opposite
color from the current pixel on the screen) The position is optional;
if omitted, it defaults to the last point done by the last DRAW, XDRAW
or HPLOT.

Drawing shapes when no shape table has been defined or loaded is a bad
idea.

& [parameters vary]
Jumps to a vector at $3F5 (1013); machine language programs may use
this as a hook to calling them. Smarter programs can be passed
parameters; the exact syntax for those depends on the program.
_________________________________________________________________

Section 7: Error codes and messages

7.1: Applesoft Error codes

Following is a list of the error codes returned on a PEEK(222), as
well as the message printed if the error remains untrapped.

Code Message:
0 ?Next Without For
16 ?Syntax Error
22 ?Return Without Gosub
42 ?Out of Data
53 ?Illegal Quantity
69 ?Overflow
77 ?Out of Memory
90 ?Undefined Statement
107 ?Bad Subscript Error
120 ?Redim'd Array
133 ?Division By Zero
163 ?Type Mismatch
176 ?String Too Long
191 ?Formula Too Complex
224 ?Undef'd Function
254 ?Reenter
255 (Control-C interrupt)

Error codes not possible within a program:

?Can't Continue Error
?Illegal Direct Error