Thanks for the reply, forte1320. :nod:
This is just an exercise and some of the common rules are disregarded, at this point of the studies (I'm reading and making exercises from Arnold Schoenberg's Theory of Harmony). So, some "errors" on doublings and some other things are intencional. But, now talking about the program, the rules are according the classical textbooks and generally, when there's something wrong about doublings, it points a doubling error and not some other problem caused by it. Every error comes along with a brief explanation of why it is an error. In this case, it says the following:
Bass and tenor may reach the maximum distance of two octaves. With open parts, the other pair of consecutive voices should be kept within the octave. With close parts, tenor and soprano should not overstep the distance of an octave.
So, nothing is said between alto and bass.
Thanks
BTW, a link to the program site...it's freeware and very useful.http://harmonypractice.altervista.org/HPWebSiteEn/index.html