This is used to define conditional parsing identifiers for a single project, or for all projects. Condition values are used to interpret #if and #ifdef statements. They are typically defined as constants using #define statements, or in compiler command line options, or in your IDE settings. See: Conditional Parsing and Preprocessor Support.
Source Insight maintains two sets of conditions: a global list applies to all projects, and the project-specific list applies only to the current project. The project-specific condition values are stored with each project. To access this dialog, select Options > Preferences: Languages, then click the corresponding "Conditions" button.
Add / Delete
Use this to add a new condition identifier and its value, or to delete entries in the list.
Edit...
Use this to edit the value of the selected identifier in the list.
Import / Export...
You can import or export the current condition list.
Scan Files...
This will scan your project’s source files to determine what conditional identifiers are used, and their defined values, if any. The results are put into the list. Note that the value of "Ignore Condition" means that Source Insight assumes the value is unknown, and will ignore preprocessor statements that use that condition identifier.