<Li> the dark blue background makes it difficult to alter preserving <Ul> <Li> the approved drawing during use </Li> <Li> a record of the approved specifications </Li> <Li> the history of alterations recorded on the sheet </Li> <Li> the references to other drawings </Li> </Ul> </Li> <Ul> <Li> the approved drawing during use </Li> <Li> a record of the approved specifications </Li> <Li> the history of alterations recorded on the sheet </Li> <Li> the references to other drawings </Li> </Ul> <Li> the approved drawing during use </Li> <Li> a record of the approved specifications </Li>

Which is known as the blue print of research