ZAPD XML specification (#194)

* Make XML spec

* Clarify some wording

1 files changed, 52 insertions, 0 deletions

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+# ZAPD XML specification
+
+ZAPD XMLs use a restrictive subset of the XML standard: any ZAPD XML must be a valid XML (All elements starting with `<tag>` ending appropriately with `</tag>`, single "empty-element" tags with `/` at the end, etc.). 
+
+Reminder that in
+```xml
+<a>
+    <b1>
+        <c/>
+    </b1>
+    <b2>
+        <d/>
+    </b2>
+    <e/>
+</a>
+```
+`<b1>`, `<b2>`, `<e/>` are *children* of `<a>`, but `<c/>` is not. `<c/>` is a *descendent* of `<a>` and a child of `<b>`.
+
+- Every XML's outermost element start/end tag is a single `<Root>`.
+- The children of a `<Root>` must be `<File>`s.
+- A `<File>` has *resources* as children. A resource is almost always single empty-element tag, and has one of the types
+    - `<Texture>`
+    - `<Background>`
+    - `<Blob>`
+    - `<DList>`
+    - `<TextureAnimation>`
+    - `<Scene>`
+    - `<Room>`
+    - `<AltHeader>`
+    - `<Animation>`
+    - `<PlayerAnimation>`
+    - `<CurveAnimation>`
+    - `<LegacyAnimation>`
+    - `<Skeleton>`
+    - `<LimbTable>`
+    - `<Limb>`
+    - `<Symbol>`
+    - `<Collision>`
+    - `<Scalar>`
+    - `<Vector>`
+    - `<Vtx>`
+    - `<Mtx>`
+    - `<Cutscene>`
+    - `<Array>`
+    - `<Path>`
+
+- A `<File>` cannot descend from a `<File>`.
+- All resources must be children of a `<File>`.
+- `<Array>` is the only paired resource tag enclosing an element; the element must be a single resource tag, one of
+    - `<Scalar>`
+    - `<Vector>`
+    - `<Vtx>`