user5254: It looks to me like each input to a bitcoin transaction has an index that specifies only one output from the input its spending. Is there a way to specify more than one output index, or do you have to create a second input line that contains the same input ID with a different index? It seems like that second way is wasteful of blockchain space - I would have thought there would be a way to simply specify multiple indexes. Is there a way to do that? 

user208: 
It looks to me like each input to a bitcoin transaction has an index that specifies only one output from the input its spending.

That is correct.

Is there a way to specify more than one output index, or do you have to create a second input line that contains the same input ID with a different index?

You have to add an extra input, which repeats the txid.

It seems like that second way is wasteful of blockchain space - I would have thought there would be a way to simply specify multiple indexes.

It is wasteful, but only slightly. In your hypothetical system, you still need a signature/scriptSig/witness for each of the coins being spent (unless you also want to incentivize key reuse), which are generally larger than a repetition of a txid.

Is there a way to do that?

No.

5254: <p>It <a href="https://en.bitcoin.it/wiki/Transaction#general_format_.28inside_a_block.29_of_each_input_of_a_transaction_-_Txin" rel="nofollow noreferrer">looks to me</a> like each input to a bitcoin transaction has an index that specifies only one output from the input its spending. Is there a way to specify more than one output index, or do you have to create a second input line that contains the same input ID with a different index? It seems like that second way is wasteful of blockchain space - I would have thought there would be a way to simply specify multiple indexes. Is there a way to do that? </p>
 208: <blockquote>
  <p>It looks to me like each input to a bitcoin transaction has an index that specifies only one output from the input its spending.</p>
</blockquote>

<p>That is correct.</p>

<blockquote>
  <p>Is there a way to specify more than one output index, or do you have to create a second input line that contains the same input ID with a different index?</p>
</blockquote>

<p>You have to add an extra input, which repeats the txid.</p>

<blockquote>
  <p>It seems like that second way is wasteful of blockchain space - I would have thought there would be a way to simply specify multiple indexes.</p>
</blockquote>

<p>It is wasteful, but only slightly. In your hypothetical system, you still need a signature/scriptSig/witness for each of the coins being spent (unless you also want to incentivize key reuse), which are generally larger than a repetition of a txid.</p>

<blockquote>
  <p>Is there a way to do that?</p>
</blockquote>

<p>No.</p>
