Checkboxes are used for fitting the parameters to support peaks. See page "Support Peaks" for more information.
Additional detector materials can be added in the Preferences.
If the detector material is unkonwn, but the linear absorption coefficient is known, set the detector material to <unknown> and enter the absorption coefficient directly.
The profile calculation applies a 2θ dependent correction of the intensity if a significant amount of the radiation passes the detector layer without being absorbed. Both the wavelength and absorption coefficient must be known for the transparency correction. To disable the intensity correction, enter an absorption coefficient of 0.0.