[yocto] how to understand the "PACKAGECONFIG_class-nativesdk " and "PACKAGECONFIG_class-target" ?

[tugouxp]

how to understand the two:
"PACKAGECONFIG_class_target
PACKAGECONFIG_class-nativesdk "
semantics in bb files? i did not found any explanation on the official document,  so, please help me ,thanks !
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.yoctoproject.org/pipermail/yocto/attachments/20180821/09f3e2f2/attachment.html>