What is AML:

Arc Macro Language (AML) Programming for Task-Oriented Customization

A high-level, interpretive language, meaning that an AML program is processed (interpreted) line-by-line by the AML processor before the command contained in each line is submitted to ARC/INFO for execution.
AML provides for graphical menu generation, variable substitution, logical branching, and looping.
Types of AML elements:

Directives (led by ‘&’. Instruct AML to perform the desired AML operation)

non-direct passing of information (such as variables, arguments) to ARC/INFO programs

Variables (for holding character strings, integers, real numbers, Boolean expressions, etc.)

&setvar (or &sv, even &s) to assign a value to a variable (e.g., &s covername = ‘soil)s’
use the percent sign (%) as brackets to reference the variable (e.g., &type %covername%).

Functions (a complex substitution, signaled by the square brackets ‘[ ]’)

for variable assignment (e.g., &setvar device = [response ‘Enter a station file’].).br> direct use (e.g., SHADESET [getchoice color bw -prompt ‘Select Color or B/W shades:’].

Comment statements (any statement started with ‘/*’)

Line continuation (‘~’) and line separation (‘;’)

Create and run an AML program (&watch and &watch &off; &cwta; and &run)

Local and global variables

a global variable is indicated by a dot (‘.’) in front of it (e.g., ‘.coverage’)
the scope of accessibility (a global variable remains effective in the entire ARC/INFO session).

Passing arguments to an AML program (&ARGS with tokens)

(&args dev; &station %dev%; ARCPLOT; &return ® saved as ex4.aml)

Flow of control in an AML program

&IF <logical_expression> &THEN <statement> &ELSE <statement>

[null %variable%] - evaluating a variable and returning a Boolean value (i.e., .TRUE. or .FALSE.).

the &DO ... &END block for executing several statements as a result of some logical expression.

The [SHOW] function - used to query system information for further actions

&TYPE [show pagesize] => showing the maximum x, y coordinates of the page

&TYPE [extract 1 [show pagesize]]; &TYPE [extract 2 [show pagesize]]

Looping mechanisms

Counted loop (counting toward a value given at the beginning of the looping)

&DO index := 1 &TO 10
&RUN operation.aml /* perform some operation 10 times
&END

&DO &WHILE loop (looping until the test condition is met)

&DO &WHILE not %done%
&RUN operation.aml; &setvar done := [query ‘Do you want to quit’ .true.]
&END

&DO &LIST loop (looping until a list is exhaused)

&sv color = 0
&DO coverage &LIST ROADS SREAMS CONTOURS
&sv color = %color% + 1
LINECOLOR %color%
ARCS %coverage%
&END

AML menus (with a suffix ‘.menu’ for a menu file, and &MENU to run a menu file)

utility - supply a list of choices on the terminal from which a selection can be made.
seven types of menus (pulldown, sidebar, matrix, key, tablet, digitizer, and form).
the layout of statements in a menu file (i.e., menu code and indentation).