Use together with XS_DEFAULT_LICENSE and XS_DEFAULT_ENVIRONMENT for bypassing the login dialog. Set these advanced options in a separate initialization file, and point to that file using the -I (capital i) parameter in the Tekla Structures shortcut. The parameter is used to point to a file which needs to be read before other initialization files.
Warning: If roles are used in your environment, both XS_DEFAULT_ENVIRONMENT and XS_DEFAULT_ROLE should be set for the startup to work correctly. XS_DEFAULT_LICENSE is optional.