what constitutes legal flank contact

see what you are saying Menacussecundus, and technically it would appear that you are correct.

Normally, when a single element contacts anybody, it has to conform (i.e. get those corners touching).
But in the original picture, it cannot, because there isn’t enough space to do so.
And the moving Cv can’t invoke the “Physically Blocked” rule, because that only applies when conforming to a front-edge.
Nor can the Cv claim that the Ax will turn-to-face the flank attack, as “Turning-to-Face” only occurs after the Move Phase has ended.
All we have is page 9 paragraph 9, which says “At the end of the bound’s movement phase, elements must be aligned”.
(i.e. corner-to-corner)

Ah, but page 9 paragraph 10, last sentence, says:-
“Unless turning to face a flank or rear contact, contacted elements conform on contact”
This is explained by the January 2018 FAQ as:-
Q: I have a line of cavalry that moves into contact with the side edge of a single Light Horse element. Does the Light Horse turn to face immediately or only at the end of the movement phase?
A: At the end of movement. If the contact is not in front edge to side edge contact with front corners in contact, the Light Horse conforms immediately. The turn occurs after the movement phase.

Soooo...using my flowchart:-
　　The Cv moves into contact with the Ax flank, and should conform but cannot because there isn’t enough room.
　　So the Ax has to do the conforming instead (contacted elements conform on contact).
　　But how can the Ax conform if it can’t turn-to-face just yet?
　　Simple...it moves it’s front corner to touch the Cv front corner, thus ending the Movement Phase legally aligned.
Once all movement is completed and the Move Phase has ended, the Ax will turn-to-face.

This is a better than saying “the general principle that troops that would make contact in real life do so in the game” is a lie.
And if the Ax had someone behind it so it’s impossible to get the corners touching, like in the original picture, it’s better than having an element that is immune to ever being attacked at all! (except on it’s front).
Surely that would be absurd.

There are other contractions in the “Moving into Contact” rules on page 11.
Page 9 paragraph 9 says “the contacting (i.e. moving) troops must conform”…
Page 9 paragraph 10 says “unless turning to face, the contacted (i.e. stationary) elements conform on contact”…
So which is it?
Is it the moving troops that have to conform...or it it the stationary troops?
Both of these lines then get contradicted by the who-conforms-to-who rule!

Seems to me that the conforming rules could do with a bit of a shake-up...



Some potentially useful player aids can be found here, such as the “Quick Reference Sheets” from the Society of Ancients,
and the new “Army List Corrections” file: fanaticus-dba.wikia.com/wiki/Category:Reference_sheets_and_epitomes
And this is the latest January 2018 FAQ: fanaticus-dba.wikia.com/wiki/FAQ_2018

Napoleonic Squares!

None of these elements can ever be attacked in the flank!



(But I’m not sure that such a formation was ever used in the ancient period however...especially with gaps between the elements leaving their flanks wide open to attack...) 

Fair enough Joe. 

I should point out I am a great believer in the DBA rules...at least when they give plausible realistic results.

Can anyone give a good, logical, valid, real-life reason why charging a flank as shown in the original picture should be disallowed?
Or is it nothing more than an artificial side effect caused by the way the current contact and conforming rules have been worded?

Still, providing both players follow the same rules the game works fine...even if it doesn’t make sense sometimes.



Some potentially useful player aids can be found here, such as the “Quick Reference Sheets” from the Society of Ancients,
and the new “Army List Corrections” file: fanaticus-dba.wikia.com/wiki/Category:Reference_sheets_and_epitomes
And this is the latest January 2018 FAQ: fanaticus-dba.wikia.com/wiki/FAQ_2018

That is a very good analysis Tom, and I thank you for it.

DBA 3.0 has made great strides into improving the contact and conforming rules, and eliminating many of the unrealistic cheesy gamey geometric ploys that plagued DBA 2.2. But unfortunately, a few of these still remain. And the case in point is one of them.

The current problem arises from page 9 paragraph 10 where it says “If conforming to a front-edge by contactors is prevented...”.
Why limit it to just the front-edge?
Rather than encouraging the general principle that troops that would contact in real life do so in the game, this front-edge only limitation is actually preventing real life contact. It would be far better if this line simply said “If conforming is prevented...”

But the rules have already been written, so one way out of this dilemma (other than re-writing the rules) is to apply ALL the rules as currently written. I am referring to the last sentence of page 9 paragraph 10, which says:-
“Unless turning to face a flank or rear attack, contacted elements conform on contact.”

Enforcing this rule (which is already written in the rules and is there for all to see) would give the following sequence of events:-
        The Cv moves into contact with the flank of the Ax and conforms as best it can.
        Applying the "contacted elements conform on contact rule", the Ax has to complete the conforming.
        The Ax does this by moving its front-corner to touch the Cv front-corner, but won’t turn to face just yet.
        After the movement phase has ended, the Ax turns to face the flank attack.

(I’m assuming that if players object to leaving out the words ‘front-edge’ in the “If conforming to a front-edge by contactors is prevented...”, they will also object to leaving out the “contacted elements conform on contact.” rule.
Either use ALL the rules as they are written, or leave some of the words out...you can’t have it both ways)

Still, should the DBA community wish to keep this unrealistic geometric ploy, and ignore the “contacted elements conform on contact” rule, then expect to see more formations like this on your table-top battlefields:-

                 Bd  Bd  Bd  Bd  Bd  Bd  Bd  Bd  Bd  Bd 

                                              Sp  Sp  Sp  Sp  Sp
                          <--- facing  Sp
                          <--- facing  Sp
  
The Spears with the open unprotected sides can never be attacked in the flank, so the best that Blades can do is get an overlap on the end Spear element and somehow wiggle a Blade group to swing round to face the separate Spear group frontally...which will take time and cost PIPs.
(Good for those pike armies that have a short battleline I suppose...)

Thanks for pointing out all those contradictions Menacussecundus. 

Rule 9.9: “the contacting (i.e moving) troops must lined-up and conform, corner-to-corner, etc...”
Rule 9.10: “contacted (i.e stationary) troops conform on contact...”
Also Rule 9.10: “sometimes the moving troops have to conform, and sometimes the stationary troops have to...”

These three lines can’t all be true.
I would be happy to play by the rules...but which rule do I play by?
(I assume the third line overrides the first two...which means the first two lines must be wrong and are not telling the truth).

I’d much rather follow the principle that “moving a front-edge into contact with an enemy ALWAYS results in combat”.
(Which is itself contradicted by the need to have the front-corners touching as well)

I'm just trying to find a way to avoid absurd situations where an element is totally immune from being attacked in the flank.
Encouraging real-life contact is better than having rules that deliberately use artificial gamey geometric ploys that prevent it...


P.S.
It would have been better if those first three lines above had said:-

Rule 9.9: “the conforming troops must lined-up and conform, corner-to-corner, etc...”
Rule 9.10: “conforming troops conform on contact...”
Also Rule 9.10: “sometimes the moving troops have to conform, and sometimes the stationary troops have to...”
And if the conforming troops are physically blocked and cannot conform, then the enemy must conform instead.

...then there would have been no contradictions.