1. A method for producing N-bit output words of RLL-encoded data having both a global constraint G o and an interleave constraint I o on bits of a first value, the method comprising: receiving N-bit input words of RLL-encoded data having both a global constraint G i and an interleave constraint I i on bits of like value; and producing the output words from respective input words by sliding-window encoding of each input word to replace predetermined bit-sequences with respective substitute sequences such that G o <G i ; wherein each substitute sequence is unique and violates a run-length limit associated with the interleave constraint I i such that I o >I i .