Starting today, if you are a U.S. resident (and if you’re not stay tuned—they’ll be expanding soon), you can take dozens of the MCP and MTA exams from the comfort of your home or office through a process called online proctoring by Pearson VUE. Or as Ken Rosen says "Come on, admit it: you’ve always wanted to take one of our exams in your pajamas. I can’t be the only one."
When you look at the list of exams available you will find numbers like 462-OP (on premise?). Add a 70 in front of the number and remove the "-OP" to find the equivalent exam ID. (70-462). The "98" series exams just have the normal number with "-OP" added to the end.
Here are some of the "OP Beta" exams that are "in my world" (SharePoint, SQL, etc.):
346-OP Managing Office 365 Identities and Requirements
347-OP Enabling Office 365 Services
410-OP Installing and Configuring Windows Server 2012
411-OP Administering Windows Server 2012
412-OP Configuring Advanced Windows Server 2012 Services
461-OP Querying Microsoft SQL Server 2012
462-OP Administering Microsoft SQL Server 2012 Databases
463-OP Implementing a Data Warehouse with Microsoft SQL Server 2012