The following advice is not meant to be considered a specialized handbook, therefore it will not deal with technical problems concerning frame construction. This is only a helpful tool for those who have to cope occasionally or by chance with the problem of frames and the relationship they have with their surrounding space and environment.
Therefore, it does not address professional installers and operators, who are supposed to be already acquainted with the concepts here explained.
It may happen that someone who is not a specialist has to change doors and windows or to install new frames.
Those people will find here stated some cultural, formal and usage parameters that may be useful or at least underline the need to apply to a professional, should individual choice and operating skills not be suitable to solve the problem.