Oh noes! I am stuck on the concepts of UV mapping; more specifically, how Vector3 positions correspond to Vector2 coordinates.

I have made a simple code for a 'box' prefab:

 using System.Collections.Generic;
 using UnityEngine;
 
 namespace Assets.Scripts
 {
     class BoxProcedural : MonoBehaviour
     {
         public int length;
         public int width;
         public int height;
 
         void Awake()
         {
 
         }
 
         void Start()
         {
             Mesh mesh = gameObject.AddComponent<MeshFilter>().mesh;
             MeshRenderer meshRenderer = gameObject.AddComponent<MeshRenderer>();
 
             mesh.vertices = new Vector3[]
             {
             new Vector3
                 (
                 transform.position.x - (width / 2.0f),
                 transform.position.y - (height / 2.0f),
                 transform.position.z - (length / 2.0f)
                 ),
             new Vector3
                 (
                 transform.position.x + (width / 2.0f),
                 transform.position.y - (height / 2.0f),
                 transform.position.z - (length / 2.0f)
                 ),
             new Vector3
                 (
                 transform.position.x - (width / 2.0f),
                 transform.position.y - (height / 2.0f),
                 transform.position.z + (length / 2.0f)
                 ),
             new Vector3
                 (
                 transform.position.x + (width / 2.0f),
                 transform.position.y - (height / 2.0f),
                 transform.position.z + (length / 2.0f)
                 ),
             new Vector3
                 (
                 transform.position.x - (width / 2.0f),
                 transform.position.y + (height / 2.0f),
                 transform.position.z - (length / 2.0f)
                 ),
             new Vector3
                 (
                 transform.position.x + (width / 2.0f),
                 transform.position.y + (height / 2.0f),
                 transform.position.z - (length / 2.0f)
                 ),
             new Vector3
                 (
                 transform.position.x - (width / 2.0f),
                 transform.position.y + (height / 2.0f),
                 transform.position.z + (length / 2.0f)
                 ),
             new Vector3
                 (
                 transform.position.x + (width / 2.0f),
                 transform.position.y + (height / 2.0f),
                 transform.position.z + (length / 2.0f)
                 )
             };
 
             mesh.triangles = new int[36]
             {
                 0, 2, 3,
                 3, 1, 0,
                 1, 5, 4,
                 4, 0, 1,
                 3, 7, 5,
                 5, 1, 3,
                 2, 6, 7,
                 7, 3, 2,
                 0, 4, 6,
                 6, 2, 0,
                 5, 7, 6,
                 6, 4, 5
             };
 
             mesh.RecalculateNormals();
         }
 
         void Update()
         {
 
         }
 
         void OnGUI()
         {
 
         }
     }
 }

The code makes me a cubic 'box' interior to be used as a room. Now I want to implement UV mapping for each face, with the aim of altering material parameters (i.e. tiling and texture) for each face individually. I would like to type in the code for the UV coordinates manually as I have done for the vertices and triangles, a) because I would like to see the pattern behind the process, b) because I would like to be able to alter UV mapping code if required at a later date.

Could someone post me the Vector2 UV mapping coordinates for the box, or even a single face, so that I can get the principal? Many thanks in advance!