Poser Flavors
Anything created in Poser 4 can be used in Poser Pro Pack (PPP) and Poser 5. Most things created in PPP can be used in P4 and P5, and some things in P5 are backwards compatible. Listed below are some major differences.
Version Number
P4 - items referenced for P4 will have version number 4.03 (assuming the latest P4 patch has been run. If you have an earlier version than 4.03, you really should run over to Curious Labs and download the patch!)
PPP - 4.2.0.160.
P5 - 5.02.268.
What does this mean? If you use an item and get the error "Version number later than expected" then the file was created in a later version of Poser. Click Okay and it should still load properly. Certain items, such as bump maps, will not work.
To avoid this problem, crack open your text files, such as .cr2 and .pz2 files and change the version at the top of the file to read as follows:
version
{
number 4.03
}
Library Thumbnails
P4 uses .rsr files. I have no clue where that file type came from. P3d0 Explorer by Seno Software can open these files up and display them.
If you only have .png files, P3d0 can convert them into .rsr files with a .rsr <-> .png converter plugin. (It's wonderful!)
PPP and P5 use .png files.
If you have an item with .rsr files as library thumbnails, open up the library folder in PPP or P5 and it will automatically create .png files for you. After that, you can delete the .rsr files.
Tip: if you have PPP or P5 and the library thumbnails are blank, close Poser, convert them to .rsr in P3d0 Explorer, then delete the .png files. Open Poser back up and it will recreate the .png files, and the thumbnails will come back. If a .png file is created incorrected, PPP and P5 will not show anything, but P3d0 is capable of translating the file to .rsr anyway.
What does this mean? To make things as compatible as possible, you can create just .rsr thumbnails as PPP and P5 will convert them on the fly. If you want, you can include both .rsr and .png and include instructions on which set of files to delete.
Bump Maps
P4 uses .bum files. .bum is a special translation of a Windows .bmp file. It's freaking huge in size!
If you get a .jpg file for your bump map, use a graphics converter to change it to .bmp. Open up Poser and load the texture. When you point P4 to the .bmp file for the bump map, Poser will offer to convert it for you. Click Yes.
PPP and P5 use .jpg files.
If you only get a .bum file, you can rename it to .bmp and use a graphics program to convert it to .jpg. You may get a bit of degredation, but at least it's usable.
What does this mean? A headache. Not only does this affect what files to include for the bump maps, but if you create MAT files, they will be different for P4 than PPP and P5. The easiest solution is to create .bum and .jpg bump maps and create 2 sets of MAT files, one referencing the .bum files, the other referencing the .jpg files and hope that people read the readme. The problem is, this adds a lot of size to the download. Another option is to create 2 sets of downloads, one for P4, the other for PPP/P5.
If you don't want to create 2 sets of downloads, one for P4, the other for PPP and P5, my personal suggestion is to create the bump maps as .bmp files. In the readme, give instructions on how to convert them to .jpg files for PPP and P5, and to instruct P4 users on how to call up the bump map so Poser converts it automatically. The MAT files aren't very big, so you could have 2 folders, one for P4, the other for PPP/P5 MATs. You would then have the library thumbnails as .rsr files in the P4 folder, and the .png files in the PPP/P5 folder.
Materials
P4 and PPP - this simply means how the object has been grouped for coloring. Materials can include eyes, skin, etc.
P5 - not only does it have materials for texture grouping, but it has a seperate Material file (.mt5) which is a special texture map. It can be considered a description of a how to create a texture, such as add 10 drops of red #5, 5 drops of Cadmium Yellow, etc. instead of having the physical paint tube. If you use a program like Bryce, Vue d'Esprit or 3DS Max, then you've seen these same types of Materials. Only P5 can use these files.
What does this mean? Angry, confused e-mails if you don't clearly label .mt5 files as being for P5 only.
Hair
There's a lot of different ways to do hair now. Some hair files are props that are specially created for the head. These are .hr2 files in the Hair library. Some hair files are regular Props. A few hairstyles are conforming Figures in the character library. Then there's P5.
P4 and PPP - hair works the same.
P5 - new type of hair that looks more like strands of hair and can be more easily animated. It is found in the Hair folder, in the Poser 5 Hair subcategory. These files can be .hr2 or .hrz. (.hrz means that it is compressed.)
What does this mean? P5 hair is not backwards compatible. If you have a .hr2 file that doesn't work, open up the file in Notepad/Wordpad, etc., and look at the version. If it is version 5, it will only work in P5. (Changing the version number will not help. Nice try.) The only other possible problems would be items discussed earlier, such as library thumbnails or bump maps.
Python
Python is a programming script to automate tasks.
P4 - not supported.
PPP and P5 - supported. I've heard that there are some minor differences, but every script written for PPP that I've run has worked fine for P5.
What does this mean? Don't download it if you have P4 unless you're about to upgrade. If you have PPP or P5, there is a small chance that a script might not work if it was written for the other version, but I haven't heard of a script failing yet.
These are the major issues so far between the various Poser flavors. If I've missed any, please drop me a line.