A vanilla calendar spread is a widely-used strategy that involves simultaneously buying one option and selling another (that is: a long call and a short call; or a long call and a short put; or a long put and a short call; or a long put and a short put).
The only condition is that each option has a different expiry date; the strikes and notionals can be the same or different. If you enter the same expiry date for each option, it is no longer a calendar spread. Instead it creates a call spread (for a long call and short call), a put spread (for a long put and short put), or a risk reversal (long put and short call or long call and short put).
Pricing a calendar spread in SDX Commodities & Energy
You can only automatically enter into this instrument in the Single Option page.
To price a vanilla calendar spread in the Portfolio page, you need to build it manually out of its individual components.