...

A bed sheet is a rectangular piece of cloth used either singly or in a pair as bedding, which is larger in length and width than a mattress, and which is placed immediately above a mattress or bed, but below blankets and other bedding (such as comforters and bedspreads). A bottom sheet is laid above the mattress, and may be either a flat sheet or a fitted sheet (a sheet which has been sewn with elastic or a drawstring along the hem of the top, sides and bottom of the sheet to prevent it from slipping off of the mattress). A top sheet, in the many countries where they are used, is a flat sheet, which is placed above a bottom sheet and below other bedding.

...

Fit and style are also vital. Fitted sheets with deep pockets can accommodate thicker mattresses commonly found in motorhomes Fitted sheets with deep pockets can accommodate thicker mattresses commonly found in motorhomes Fitted sheets with deep pockets can accommodate thicker mattresses commonly found in motorhomes Fitted sheets with deep pockets can accommodate thicker mattresses commonly found in motorhomesmotorhome sheets that fit. Elastic all around the sheet ensures it stays in place during transit. Flat sheets with generous dimensions allow for easy tucking and less likelihood of coming loose.

...