title: what is the difference between var.op.name and var.name in tensorflow?
body: <p>I have one point confusing. Here is the example code:</p>
  
  <pre><code>opt = tf.train.GradientDescentOptimizer(1e-4)
  grads_and_vars = opt.compute_gradients(total_loss)       
  for grad, var in grads_and_vars:        
      print(var.op.name)
  </code></pre>
  
  <p>the output is: <code>conv1/filt conv1/bias</code></p>
  
  <p>and when I change <code>var.op.name</code> into <code>var.name</code></p>
  
  <p>the output is: <code>conv1/filt:0 conv1/bias:0</code></p>
  
  <p>What is the difference between <code>var.op.name</code> and <code>var.name</code>? 
  and what does <code>:0</code> mean?</p>