why do most file formats define a start of file marker? -

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for instance jpeg (jfif) has soi (start of image) marker. 1 can argue can used identify type of file, i'm looking more sound reason supporting examples.

these referred "signature bytes" , primary purpose aide in validating file. file types contain additional signature bytes elsewhere in file (ie: bmp format), , contain none @ all. latter kind still provide other means validate file using variety of techniques, such checksums, stored file size , like.


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