Compatible software and figure, check. Render engine, uhmm?
I was really excited about today's resources and add-ons MM sale, but soon got frustrated, because it's giving me headache to find out which render engine those resources/shaders are for. I mean, DAZ have updated for every product what DAZ Studio version it supports and what install types are available, but still some of the shaders have absolutely no information which render engine it is for. I assume, that if it does not say Iray somewhere, it's 3Delight only? Sure, that's a way to describe it, and maybe it's just me, but I find that really annoying. I think it's just plain stupid, that I have to check promo images, product description, and finally document center, and if nothing says Iray, then it's for 3Delight only....maybe. We already have compatible figures and software in main info box, so why not compatible render engines?
If I was a shader guru, I wouldn't need to buy any shaders at first place, so I think that piece of information is crucial at least for shaders, but I'd rather see it in every product. It's very confusing, especially for Genesis 2 figures/products, since some have Iray support and some not, so filtering by render engine would be a very welcome addition.
Here's one example: http://www.daz3d.com/ground-shaders-for-daz-studio where all the images just say DAZ Studio render, and in description it says 3Delight and Iray. Good, it supports Iray, but I'd still prefer that render engine information was on main info box, since usually products that support Iray have Iray logo in promo images, and here those Iray logos are nowhere to be found. Since we can't trust promo images, I hope you understand my confusion in products like this: http://www.daz3d.com/woodland-leaf-floors-daz-studio-shaders, where promo images says DAZ studio render, but it does not say anywhere for what render engine it is for. It doesn't even say 3Delight anywhere, so DAZ please, consider adding that render engine information to a visible place.

Comments
If they don't indicate Iray or Poser support, in all likelyhood they are for 3Delight.
Yes, if Iray is not explicitely mentionned then assume it's for 3Delight, or ask in the forums.
Iray was added in DS 4.8 only. Before that there was absolutely no need to say which render engine DS shaders were made for since there was only one, so a good number of products won't have that info.
Products that achieve most of their texture look through texture maps can be used in any renderer, but they will require the use of alternate shaders if the renderer of your choice is not supported. For example I have http://www.daz3d.com/woodland-leaf-floors-daz-studio-shaders, but if you apply them by double clicking to load on to the surface then nothing is seen in iRay. It uses a 3DL shader unknown to iRay. However if you apply iRay Uber, and plug the textures into the right places, then they do work in iRay. So it is more work to get them to work for you.
However there are procedural shaders around which are not largely based on texture maps, and these will only work in the supported renderer. Examples of these include the grass and rock shaders from AoA which only work with 3DL. I realise it can all be confusing, but if you do buy shader's that are no use to you, DAZ are pretty good about returning your money if you do so within 30 days of purchase.
Yes, but this one says it works in both 3Delight and Iray, and I don't see any separation in the user files that says how it is done. Most that do both have separate folders. The read me is vauge on it also. I guess we have to play with it to find out.
Anybody gonna chime in? Usually they have Materials in two versions 3D and iray.
If you open up the tips mini-pane below your smart media tab, you'll usually see a description of the material and it will say 3Delight or Iray- if the PA forgot or neglected to name the material or shader file/preset with the name iray or 3Delight.
If in doubt you can also have a look at the SDK or "Product Id" to figure out how old the product is.
Iray was introduced to DAZ Studio around March 2015 with a Beta release of 4.8.0
The lowest product Id I found in my Library with an Iray logo is SDK 21285.
Let's say the following as rules of thumb:
If a product has a lower SDK than 21000 it was very likely not created with Iray materials.
Products with an SDK between 21000 and 22000 require you to look very closely at the products description.
Products with an SDK higher than 22000 may most likely include Iray materials.
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BUT
Some selected products may have been updated with Iray versions of the shaders later.
-> The product may not have the Iray logo on the promo images but in the product description you may be able to read:
DAZ Studio Iray and 3Delight Shader Presets
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Examples:
http://www.daz3d.com/ground-shaders-for-daz-studio
SKU:21468
No Iray logo but DAZ Studio Iray and 3Delight Shader Presets
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http://www.daz3d.com/woodland-leaf-floors-daz-studio-shaders
SKU:20751
The SKU is in the 20'000s and not the 21'000s.
-> It is safe to say that this product was not created with Iray in mind.
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Of course if you do not mind the time needed you can adjust any materials on your own to make them look a bit closer to your original vision in Iray.