This page exists because it was decided that sheet is a too ambiguous of a term for a tag and it should be replaced by more specific ones:

• bed_sheet - traditionally a flat piece of fabric designed to cover a mattress, though occasionally re-purposed for other things (like covering furniture for storage, or pulled around a character for modesty, or even pillow forts).
• under_covers - when bedding, blankets or sheets are pulled up over a character's body, at least partially covering them. Most often seen while laying down or on a bed.
• grabbing_sheets - when a character is grabbing a bed_sheet, often used to show the intensity of how they're feeling (for example: during sex or masturbation)
• cum_on_sheets - when cum is seen on bed_sheets

• model_sheet - a reference sheet for a specific character: usually showing them in multiple angles or poses, explaining parts of their anatomy, colors and/or other features of their character design
• expression_sheet - a character being drawn several times to show a variety of expressions, as a reference sheet

• sheet_music - paper with written music on it. Often also needs the musical_note tag as well if the notes are distinct and not too abstractly drawn.