Related Clues:

• It shows what's missing from farm vehicle, saving energy
• Inverted v
• Sign of proofreader having attention to detail before time
• A sign of something missing? Trouble with that hat going astray
• Proofreading sign for 'Insert'
• Sign of an omission
• Word-insertion mark
• Inverted "v" mark
• Little arrow used for insertions
• Input signal?
• Mark for insertion in Building Act to cover engineers
• Manuscript insertion mark
• "Insert here" symbol
• Ahead of time, be concerned it shows where text is lacking
• Character resembling a hat