Uppercase
Uppercase - quick reference
Uppercase letters occupy ASCII codes 65-90 (A-Z), 32 positions below their lowercase equivalents. The offset is a design feature: subtracting 32 (clearing bit 5) converts lowercase to uppercase, and vice versa. Browse all 26 in the uppercase A-Z character group.
Uppercase conventions vary by context. SQL keywords are conventionally uppercase (SELECT, FROM, WHERE). Environment variables in Unix are uppercase by convention (PATH, HOME). HTTP headers use Title-Case (Content-Type). DNS is case-insensitive by spec but conventionally lowercase. In early computing, some systems only supported uppercase - the original 1963 ASCII standard lacked lowercase letters entirely, adding them in the 1967 revision. See the ASCII timeline for details.
Uppercase conventions vary by context. SQL keywords are conventionally uppercase (SELECT, FROM, WHERE). Environment variables in Unix are uppercase by convention (PATH, HOME). HTTP headers use Title-Case (Content-Type). DNS is case-insensitive by spec but conventionally lowercase. In early computing, some systems only supported uppercase - the original 1963 ASCII standard lacked lowercase letters entirely, adding them in the 1967 revision. See the ASCII timeline for details.