How to make a drag/drop script only affect objects with a tag?

So, Unity’s Standard Assets as script that makes objects with rigidbodies capable of being dragged around with the mouse in 3D. The problem is that I’ve just started C# because of Unity and all my tries in order to make it only affect objects with a “MOVE” tag have failed. I’ve searched so much stuff explaining tags but I just can’t really adapt to this one. THANK YOU SO MUCH TO ANYONE WHO TRIES TO HELP!
The script is there below. Basically, making this only affect rigidbodies tagged with a “MOVE” tag? Thank you!

using UnityEngine; 
using System.Collections; 

public class DragRigidbody : MonoBehaviour 
    public float maxDistance = 100.0f; 
    public float spring = 50.0f; 
    public float damper = 5.0f; 
    public float drag = 10.0f; 
    public float angularDrag = 5.0f; 
    public float distance = 0.2f; 
    public bool attachToCenterOfMass = false; 

    private SpringJoint springJoint; 
    void Update() 
        Camera mainCamera = FindCamera(); 
        RaycastHit hit; 
        if(!Physics.Raycast(mainCamera.ScreenPointToRay(Input.mousePosition), out hit, maxDistance)) 
        if(!hit.rigidbody || hit.rigidbody.isKinematic) 
            GameObject go = new GameObject("Rigidbody dragger"); 
            Rigidbody body = go.AddComponent<Rigidbody>(); 
            body.isKinematic = true; 
            springJoint = go.AddComponent<SpringJoint>(); 
        springJoint.transform.position = hit.point; 
            Vector3 anchor = transform.TransformDirection(hit.rigidbody.centerOfMass) + hit.rigidbody.transform.position; 
            anchor = springJoint.transform.InverseTransformPoint(anchor); 
            springJoint.anchor = anchor; 
            springJoint.anchor =; 
        springJoint.spring = spring; 
        springJoint.damper = damper; 
        springJoint.maxDistance = distance; 
        springJoint.connectedBody = hit.rigidbody; 
    IEnumerator DragObject(float distance) 
        float oldDrag             = springJoint.connectedBody.drag; 
        float oldAngularDrag     = springJoint.connectedBody.angularDrag; 
        springJoint.connectedBody.drag             = this.drag; 
        springJoint.connectedBody.angularDrag     = this.angularDrag; 
        Camera cam = FindCamera(); 
            Ray ray = cam.ScreenPointToRay(Input.mousePosition); 
            springJoint.transform.position = ray.GetPoint(distance); 
            yield return null; 
            springJoint.connectedBody.drag             = oldDrag; 
            springJoint.connectedBody.angularDrag     = oldAngularDrag; 
            springJoint.connectedBody                 = null; 
    Camera FindCamera() 
        if (camera) 
            return camera; 
            return Camera.main; 

I think your question is already answered here:

But in case it isn’t clear, the raycast method you are using writes to a hit variable:

Physics.Raycast(mainCamera.ScreenPointToRay(Input.mousePosition), out hit, maxDistance))

This hit variable has a transform object with a tag, so what I might try to do is add an if check like this:

if(hit.transform.tag != "MOVE")

Rather than using tags, you could also go for layer masks:

int movableMask = LayerMask.GetMask("Movable");
if(!Physics.Raycast(mainCamera.ScreenPointToRay(Input.mousePosition), out hit, maxDistance, movableMask))