Vref is safe the arrival in the TDZ at between Vref an Vref+5 is to me a common sense item---under most circumstances however ---see BelArgUsa's post
as long as you are not accelerating [in the real meaning] you are in steady level coordinated flight---if parameters are changing VS/ ASI then you are not in 'SLCF' however if [in my divination] have allowed yourself the correct altitude/airspeed buffers it is possible to alter the flight path and resume SLCF---by making trim and power changes------
but that is steady level coordinated flight
---to be stable for
landing you must first acheive force vector equilibrium, thence remain with in the performance parameters dictated by the OEM/certification authorityn and the Air carrier rules and coomon sense
now, many folks get SLCF confused with stable
they are different --- One can be stable at VMO
However,
----by acheiving and remaining in SLCF the are several benefits acceleration noted on the instument give advance notice of event like gust or windshear
----engine thrust should be quite close to that required for fast spool up to aprch and ldg climb thrust form Vref+x
correction to mild deviatons in sink rate are easily adjusted for with thrust because the airplane will remain near trim airspeed and -- if applicable-- it makes the ol' "boeing push' real smooth like
if you're gonna get an arrival you can just drag her on in
PA