Throughout the guide "must," "should," and "can" have special meanings.
Guidelines with "must" in them are requirements for OSF/Motif Style Guide compliance. Any guideline with "must" is included in the OSF/Motif Level One Certification Checklist for OSF/Motif Style Guide compliance.
Guidelines with "should" in them are recommendations. We consider them important for interapplication consistency, but we do not require them for compliance. You should follow them as closely as you are able.
Guidelines with "can" in them indicate optional elements of user interface style.
The process for how OSF/Motif Style Guide elements migrate from options to requirements is described in the OSF/Motif Level One Certification Checklist (Appendix B).
Note that by default this guide assumes your application is being designed for a left-to-right language direction environment, and that the application is written in English. Many of these guidelines can, and in fact should, be modified based on both language and scanning direction.