Two part question: Check my Syntax please?

[Special-K]

I am certainly a novice. But I've got an elaborate Excel sheet that I've made over a long course of time. I need to expand on it and I need help.

I've got this formula below:

=IF(OR(ISBLANK(B10), ISBLANK(C10)), "", IF(A10="HD", 0.5*(C10-B10+1), C10-B10+1))

What would the syntax be if I wanted to add more items where it reads "HD"?
For example: ..... IF(A10="HD" , "PH" , "OH" , "LH" , "MH" , 0.5*(C10-B10+1, C10-B10+1))

I know my example is incorrect ... I cannot quite get it right ... either commas not in the right place, spaces ... or something. I spent quite awhile trying to find an example ... but unsuccessfully.

The second part of my question:
I have used up the three conditional formats that Excel allows.
I've got it where if "ED" is entered, the cell is formatted a particular color. Same with "LV" and "PD".

For example: .... Formula Is =(A105="LV")
Can I also include other codes here: Such as ... Formula Is =(A105="LV" , "PH" , "MH"?

I'm just not getting the syntax quite correct and would appreciate guidance.

Thanks!
Kevin.

 

[barry houdini]

Also....

=SUM(SUMIF(A5:A93,{"CO","CH"},D5:D93))