Ynrhed Eidden of The Krynn here, reporting as ordered or parsed --

Kay, let's try this again but this time, i will attempt to be much more cohesive and precise with a fairly good example.
When i was fleshing out the XW_TechTree and decided to make it a bit (lot) more leaner, some areas weren't grouping or deploying as i truly wanted too. Namely, the tricky Hulls and Buildings node.
It took me quite awhile to devise an indirect solution as i figured the obstacles to any alternative settings i'd care to slap in at mere random guesses.
Abstracted and step by step, here's what happened about two months ago. Although, i shoulda taken snapshots back then, it was easy to reproduce the process... so, take a good look at the image below with its A_B_C_D_E and/or F sections & the default values found in an XML file excerpt.

Very, very simple;
A) Grouping Hulls only. (Connections conflict!)

Grouping 1-Hulls & 2-Buildings as specifically unique. (Ooops, and this is the IMPORTANT part... SuperiorHulls_#128(yellowed off) is at the end instead of between Medium & Large Scale buildings as it should.)
C) Alright, this must be fixed... UN-grouping the Hulls but assembling Buildings only. (Ooops, once more... LargeScale (purpled off) didn't get to show SuperiorHulls as its valid preq. Besides a few more odd things creeped into the temporary structure.)
D) Re-Grouping H&B together. With a small (but maybe conflicting, btw) edit to the XML order to MOVE SuperiorHulls straight between M&L scale Buildings. Note this though; it is no longer recognized as #128 and as a result the other techs of this whole node MUST receive new numeric tags. (Ooops, the preqs aren't tied where they should either!)
E) Un-Grouping Buildings once more... only to realize; the connections are still somehow, unreadable although in the expected sequence and that if this stays as is, it would be difficult to determine the exact preqs of Hulls.
F) Final... everything as clear as possible without making MassiveScaleBuildings less important than it should since it is, in fact the last of its group.
Done, ordered as i would expect. But, not without having to edit the xml to force a single move (#128, thus becoming #123, etc) from the default tree previous location.
Connections -- non-intrusive. Sequence -- exactly right.
Now, you may say: What's this got to do with reversing or re-organizing a specific node above or below anything else even if the number of techs to the right of everything MUST be evaluated?
Much more than i believed at first before i finally nailed the parsing rules as they apply to any circumstances or modder's needs.