It is very important for an envelope to be designed properly. For example, certain types of equipment,
such as an automatic insertion machine, may have specific requirements for the insertion process to operate correctly. Grain direction also plays
a very important role in envelope manufacturing. If the grain direction of the paper is not correct, there may be excessive curling of the seal flap causing insertion problems. The parts of envelope that are important for design,
style, and measurement are shown below. Envelope terminology is usually the same, regardless
of the size or style of envelope.
