Providing vertex data to vertex programs

appdata_base: position, normal and one texture coordinate.
appdata_tan: position, tangent, normal and one texture coordinate.
appdata_full: position, tangent, normal, four texture coordinates and color.
POSITION is the vertex position, typically a float3 or float4.
NORMAL is the vertex normal, typically a float3.
TEXCOORD0 is the first UV coordinate, typically float2, float3 or float4.
TEXCOORD1, TEXCOORD2 and TEXCOORD3 are the 2nd, 3rd and 4th UV coordinates, respectively.
TANGENT is the tangent vector (used for normal mapping), typically a float4.
COLOR is the per-vertex color, typically a float4.