Hi,

I am super new to EDK2 development so excuse my ignorance.  While browsing the code base I find a lot places where the keyword "NULL" is used in place of a LibraryClass, specifically in DSC files.  For example,

in edk2/UefiPayloadPkg/UefiPayloadPkgIa32.dsc:
MdeModulePkg/Core/Dxe/DxeMain.inf {
<LibraryClasses>
NULL|MdeModulePkg/Library/LzmaCustomDecompressLib/LzmaCustomDecompressLib.inf
}

What does this mean?  Does it mean that the LzmaCustomDecompressLib.inf library instance is unconditionally linked for this package?