Original: Prime and double prime are not present in most character sets, including ASCII and Latin-1, but are present in Unicode, as characters and.
Simplified: Prime and double prime are not present in most character sets, including ASCII and Latin-1, but are present in Unicode, as characters U +2032 (dec. 8242) and U +2033 (dec. 8243), and as HTML entities & prime; and & Prime;.