> case sensitive combinations involving CTRL Historically, pressing the CTRL key would set the 6th and 7th bits of the pressed key to 0. So CTRL+J would turn

> case sensitive combinations involving CTRL Historically, pressing the CTRL key would set the 6th and 7th bits of the pressed key to 0. So CTRL+J would turn both J (1001010) and j (1101010) into Line Feed (0001010). I suppose some modern systems may have a way to distinguish between these signals, but some systems would not be able to easily generate a different signal for ^j and ^J.