TA 50, Thermo C, TA 60, Thermo B

[Milk Maid]

Me, again, trying to figure out cultures. TA 50 is Streptococcus thermophilus and slowly acidifies. TA 60 is also Streptococcus thermophilus but acidifies quickly. Thermo C is like TA 50 but with the addition of Lactobacillus helveticus. And Thermo B is a blend. Thermo C is used often in combo with Thermo B (but is it also used alone)? Is this right?

I've been using these cultures for years but realize I am not really clear on what is what.