# Specifications

Use the specifications document to view, create, modify, and save specifications files (.specs). An asterisk (*) next to a filename in the Project Explorer window and in the document tab indicates that the file has been modified but not saved.

Select File»New or click the Add Item button on the Project Explorer window toolbar to create a new document. Double-click a .specs file in the Project Explorer window or right-click the file and select Open from the context menu to launch the specifications document.

Use a specifications file to define a set of variables and associated numeric values that you can reference in levels, time sets, other specifications files, Shmoo operations, and test program code modules. You can specify the values directly or calculate the values from other variables using formulas you write with simple arithmetic expressions. Levels and timing files automatically update with value changes you make in specifications files. If you change the variable name, you must manually update any other references to the variable name.

## Configuring Specifications

Each variable must include a section name you designate by the text you type before the period (.) in the Section.Variable column. For example, the section name for the variable DC.vcc is DC. Variables must be unique within each section of a specifications file and among all specifications files associated with the test program.

Double-click or start entering data in the empty row at the bottom of the specifications table to create a new specification and specify the appropriate values. Use the reorder arrows to drag and drop specification rows to change the order of the specification definitions.

You can delete rows by selecting cells in the rows and selecting Delete Selected Specification(s) from the context menu or by selecting an entire row by clicking on the row header or selecting every cell in the row and using the <Delete> key.

You can specify the following components of each specification:

• Section.Variable — Name of the variable to use when querying the value. Variable names are case sensitive and must begin with a letter or underscore (_), are limited to A-Z, a-z, 0-9, or _ characters, and must include a period (.) to separate the section name from the variable name. Do not use math function names as variable names.
• Formula — Numeric value or formula definition for the variable. When you reference other variables to calculate a value, ensure that you use consistent units. By default, the specifications document displays the formula definition. Click the Show Formulas/Show Computed Values button to toggle the formula or numeric value view. Hover over the cell to display a tooltip with the formula and resolved value. The document highlights unresolved values and related dependencies and displays a tooltip with error information. Use the following options to specify a formula definition:

Option Valid Values Example(s)
Numeric values
5.0
-115.003
3.4E-15
150 ns
3.4 mV
Simple math operators +, -, /, *, ( ) 5.0 + (3.14 * 2)
Math functions abs, ceil, floor, fmod, sin, cos, tan, asin, acos,atan, atan2, sinh, cosh, tanh, deg, rad, pi, exp,pow, log, log10, sqrt, min, max abs(-15) * 2
Variable references AC.Variable1 * 15 where Variable1 is another specification within the AC section
Units Units: (take precedence over SI prefixes)
• V, volts, Volts, volt, Volt
• A, amps, Amps, amp, Amp, amperes, Amperes, ampere, Ampere
• s, sec, Sec, secs, Secs, second, Second, seconds, Seconds
• dB, db, decibel, Decibel, decibels, Decibels
• dBm, dbm
• H, henries, Henries, henry, Henry
• Hz, hertz, Hertz
• Ω, ohms, Ohms, ohm, Ohm
• W, watts, Watts, watt, Watt
SI Prefixes:
• d, deci (scaling factor of 1E-1)
• c, centi (scaling factor of 1E-2)
• m, milli (scaling factor of 1E-3)
• µ, u, micro (scaling factor of 1E-6)
• n, nano (scaling factor of 1E-9)
• p, pico (scaling factor of 1E-12)
• f, femto (scaling factor of 1E-15)
• da, deca (scaling factor of 1E+1)
• h, hecto (scaling factor of 1E+2)
• k, kilo (scaling factor of 1E+3)
• M, mega (scaling factor of 1E+6)
• G, giga (scaling factor of 1E+9)
• T, tera (scaling factor of 1E+12)
• P, peta (scaling factor of 1E+15)
10 ns + 15 ns
• Comment — Describes what the formula represents. This field does not accept the <Enter> or <Tab> keys.