It seems that there are 4 canonical types of conditional statements
0 - general, matter of fact real - uses present simple for both the proposition & resultant clause
"When it rains, it pours."
1 - specific real - uses present simple for proposition, but future for the resultant
"If it rains today, the streets will be flooded."
2 - unreal in the present time sense - uses irrealis imperfect (i.e., subjunctive past) for the proposition and conditional for the resultant
"I were rich, I'd be happier."
"I were to go into the army, I would not be so bored." <- pseudo-future via 'be to'
3 - unreal in the past time sense - uses past perfect for the proposition and conditional perfect for the resultant
"I had studied harder, I would have gotten better grades."
However, I think that there could be a few uses that don't fit these perfectly. I also have been seeing a lot of use that seems improper.
One of the improper uses I have been seeing is a mix between real and unreal
"Yesterday, John Boehner outlined his list of demands for raising the debt ceiling, saying that unless the Obama administration and Senate Democrats accept trillions of dollars in Republican spending cuts, the House GOP would not increase the federal debt limit, even if that leads government default, a collapse of global financial markets, and another severe recession. "
This uses present simple for the proposition clause (which indicates real), but then uses the conditional for the resultant (which indicated unreal.) I have been encountering this an awful lot, and think that this is just an improper application of what really should be unreal in the pseudo-future, i.e.,
"... unless the Obama administration and Senate Democrats were to accept ... the House GOP would not increase ..."
Another mixed case I have pondered, but think is OK, is a mix between unreal #2 & #3, for situations in which the proposition could be in the past with the resultant in the present:
"If I had studied more in college, I would be earning a higher salary today."
This to me sounds proper but it does not seem to be listed as a valid option at any English use resource. (I have pondered some other uses of tense that seem to make sense, and when I get around to it, I will offer them here.)
What do you think?
Conversely, one can also have a mixed second conditional, whose protasis refers to the present, but whose apodosis refers to the past, e.g.
If he were a better teacher, he would have been promoted long ago.