This question needs further clarifying. What kind of guidance do you mean - etiology, morphology, curve magnitude, correctibility, etc. ?

Guidence for curve magnitude and convenience of use.

I think the grading of the Scoliosis Research Society according to curve magnitude is feasible for use. It includes 7 grades. 1st grade including curves up to 20 degrees of Cobb angle, while 7th grade exceeds 125 degrees. 

Thanks for your contribution.

As Prof. Tanchev said, I would say that the SRS grading is one of the most commonly used.

However, if guidance is to be based on the existing evidence (as I think it should), I am not convinced that there is a strong basis to recommend surgery in idiopathic scoliosis, except for (questionable) esthetic purposes (see, for instance, Spine 2014:39(6):E399–E405, Spine 2013 ; 38:778–785, Spine J 2012;12:1008-1020, Spine 2012;37:592–598, Ann Intern Med 2011 Feb 1;154(3):181-189, Eur Spine J 2011;20(12):2223-2227, Lancet 2009;373(9662):463-72, Spine 2009;34(10):1094-109, Spine 2007;32:2715–2718, JAMA. 2003;289:559-567, Lancet. 1998;352(9123):229-30, Spine 1995;20: 2298-2302)

Dear Dr. Kovacs,  in my opinion not everyone with AIS should be surgically treated. But assuming that there is no medical indications for surgery  at all seems to me to be an extremal opinion.  Not only pulmonary and cardiac problems   in major and progressivec curves  should be considered candidates for sugery but also static, locomotion-related, neurologic and last but not least psychic 

Dear Dr. Kovacs,

I met with opinion, clasification Lenke is important for planning surgery. 

Dear Prof. Tanchev, I agree that many colleagues would recommend surgery for AIS based on the assumption that curve progression may hinder pulmonary and cardiac functions, or lead to pain or potential psychological consequences in the adulthood. However, when reviewing the available evidence, I noticed that it does actually not support these concerns; in fact, it suggests that AIS is virtually clinically irrelevant. Therefore, from my point of view, it is difficult to rationally justify the risks and inconveniencies from surgery.

I really enjoyed your brilliant study on scoliosis among rhythmic gymnasts (Spine 2000;25(11):1367-72); if you plan any new studies on the prognosis of (not surgically treated) AIS, don’t hesitate to let me know. It will be a pleasure to share the experience!

Thank you, Dr. Kovacs, for your appreciation  of my contributions to the study of scoliosis in gymnasts and the formulation of the "sports related scoliosis" as a separate type of scoliosis.