They're referring to the "clocking" of the lock tabs. Fact is K1-`78 have the corresponding slots, in the bar clamp itself, "clocked" a little differently, rotated such that the bars are rotated a few degrees outboard, as compared to the K0. Thus, any set of bars will have wider grip spacing when used with the K1-`78 fork assembly.
That said, while there's only one PN for the K1-`78 bar clamp, there are numerous variations in the bars themselves. The later `70s bikes (up to `78, the last year to have foldable bars) had wider spacing than the K1s & K2s. There's no definitive documentation as to when the widest version went into production. Thus some show either K3, K4 or `76 through `78 as being the same. Based on what I've seen, the late K3s (with the LH mirror mount, but no lever perch) were the first of the wide version.
That said, virtually every production run of these bars, including those carrying OER Honda PNs, has been slightly different. This goes back decades...and makes it very difficult to say which ones are "correct" for any given model/year, with any authority.
Where you'd run into problems would be trying to use early (K0-K3) on a later model that has the clamp-on switch units. The bars would fit the clamps, no problem. You would, however, need to cut-off the welded-on lever perches, they'd interfere with the switch units. The worst problem you could have using later bars on an early (K0-K2) bike would be the lack of lever perches and provisions for the early-type twist-grip throttle assembly...easily remedied with clamp-on lever assemblies and an external throttle assembly.