FitNesse. UserGuide.
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variable defined: TEST_SYSTEM=slim

The SLIM Test System

Slim (Simple List Invocation Method) is an alternative to Fit. Rather than running all the HTML processing, comparisons, and colorizing in the System Under Test (SUT), Slim keeps all that behavior on in FitNesse. What executes in the SUT is a very tiny kernel that implements the Slim Protocol. This protocol is a bare bones RPC system that allows FitNesse to call functions in the SUT.

This strategy has a number of advantages:

Using the SLIM Test System

If you want a test page to be run under SLIM, you simply set the TEST_SYSTEM variable to "slim" instead of "fit".
!define TEST_SYSTEM {slim} 
If this variable is set on your page, (as it is on this page!) or on any parent page, then your page will be run with Slim. That's all there is to it.

The Slim Tables

The first cell of a slim table tells you what kind of table it is. Here are the table types so far:
Decision Table Supplies the inputs and outputs for decisions. This is similar to the Fit Column Fixture
Query Table Supplies the expected results of a query. This is similar to the Fit Row Fixture
Subset Query Table Supplies a subset of the expected results of a query.
Ordered query Table Supplies the expected results of a query. The rows are expected to be in order. This is similar to the Fit Row Fixture
Script Table A series of actions and checks. Similar to Do Fixture.
Table Table Whatever you want it to be!
Import Add a path to the fixture search path.
Comment A table that does nothing.
Scenario Table A table that can be called from other tables.

Data Types.

The data in your tables is all Strings. However your fixtures don't want to be constrained to Strings. So Slim comes with several standard data type converters that will automatically convert the strings in the tables into the data types expected by your fixtures.
See: >DataTypes.
You can also create your own custom type converters if you like.
See: >CustomTypes.

Extra Goodies that are consistent throughout all Slim tables and ports.

Exception Handling
Symbols in tables
Constructor arguments
Value comparisons
Graceful names