The error correction code capability of the linear recording density of a zone of contiguous recording tracks on a surface or volume having at lest two zones of different average linear recording density is adjusted. Each zone has associated therewith a parameter pair (r,R) defining the number of error correction bytes r to be appended to data blocks to form a codeword written to tracks within the zone and the number R.ltoreq.(r/2-1) of correctable errors in the event of a non-zero remainder detected upon readback of a codeword from a track within the zone. The r parameter controls the length of a shift register type encoder syndrome generator.