Not all operators are valid with all types of comparisons. When comparing strings, If, =, /=, >=, <= are valid, but not <. No error results, but the accuracy of the results can be affected.
For strings, the standard wild-card characters listed in Wild-Card Characters are valid. For example, if the expression (IF (= .LAYER ELEC*) EDISON) is placed in the condition, all objects in the query on layers beginning with ELEC are displayed on the layer EDISON. In addition, the operators = and /= are valid with wild cards.
For real numbers less than one, enter all decimal values with a leading zero; that is, enter .001 as 0.001.
When nil is a possible parameter, AutoCAD Map 3D uses zero.
The expression evaluator deals only in strings; it does not distinguish between strings and numerics. The expression evaluator converts strings to their numeric values for math operations and converts the results back to strings.
If you use variables set using AutoLISP, you must precede the variable with an exclamation point (!).
To keep a space within a string, enclose the string in quotation marks. For example, "this string" evaluates as one string, with a space between the two words. Without the quotation marks, this string evaluates as two separate strings. The expression evaluator ignores quotation marks.
You must enclose named objects with spaces in the name in parentheses when used in evaluator functions. These objects include layers, blocks, hatches, and linetypes.
The following expressions handle a maximum of three arguments: +, –, *, /, AND, OR, STRCAT, =, and /=. All other expressions handle one or two arguments. If you use +, –, *, or /, you must supply more than one argument. For example, (+ 5 6) evaluates to 11; (+ 5 3 2) evaluates to 10.
An expression evaluates numbers with scientific notation in compound simple expressions. For example, (+ 1e+001 1) evaluates to 11.0000; 1e+001 evaluates to 10.0.
AutoCAD Map 3D evaluates pi only in compound expressions; the program treats pi as a string in simple expressions. For example, (STRCAT pi "_%") evaluates to 3.14%; pi by itself evaluates to "pi."
You can specify color using ACI, True Color, or Color Book color values.