# TFC Types at Openings with Conditions

The detailed construction of openings (doors, windows, niches) is determined by the selection of HRB types. The usual combinations are stored in the corresponding settings; if something changes for an individual opening, you must select the corresponding HRB types.

The selection of HRB types is based on various rules. Since version 19.01, these can also be defined as a condition on the HRB type in the HRB editor. If an HRB type has such a condition, it will only be executed if the condition is met.

Thus, in the opening setting within the plan input you can enter all HRB types that are possible. Within the HRB system itself, the condition then determines which HRB type ultimately gets executed. It is particularly convenient if all HRB types in the HRB editor have been assigned conditions; then you can check the checkbox "*use all HRB types with satisfied conditions*" in the opening setting (in the plan). The system then checks all HRB types present in the HRB pre-run and executes those whose conditions are satisfied.

Notes on conditions for HRB types:

* In the condition you can access all system variables available in HRB: wall information, opening dimensions, etc. You can therefore, for example, formulate conditions based on the opening width.
* All variables of the HRB file can be checked. It is particularly noteworthy that for external variables the value can be taken from the first combined element of the window (door, niche) (see also compendium **CombinedElements\_Udxx**, chapter "*Variables and intermediate values of combined elements in openings (doors, windows and niches)*"). Thus, if, for example, the type of shading is specified in the first combined element of the window, this information can be passed through to HRB via the variables and processed there in conditions of the HRB type. Only HRB types appropriate for the shading will then be executed.
* All intermediate values of the HRB file can be checked. To perform more complex checks, you can therefore make the corresponding pre-calculations in the intermediate values.
* General notes on formulating conditions can be found in **Variables\_Udxx**, chapter "*Comparisons that can be used in conditions"*. Note: Entering the conditions here is sufficient; this is not a conditional formula.
