Most of these codes can be seen as a kind of Run Length Limited code.

RLL Run Length Limited an improved data storage system giving 13k per track on most dumb drives.

Run Length Limited (RLL)

ST412 was available in either MFM or RLL (Run Length Limited) encoding variants.

For reliable clock recovery at the receiver, one usually imposes a Run Length Limited on the generated channel sequence, i.e. the maximum number of consecutive ones or zeros is bounded to a reasonable number.

Ones-density is often controlled using precoding techniques such as Run Length Limited encoding, where the PCM code is expanded into a slightly longer code with a guaranteed bound on ones-density before modulation into the channel.