Choosing between full .NET framework and .NET Core as ASP.NET Core target? -

i extending system uses .net 4.5 . need:

1. the other projects able reference new .net core libraries.
2. my .net core projects able reference our .net 4 libraries.

aside question of 1 target, have noticed vs 2017 not give me option target .net core when creating new project.

.net core libraries .net standard libraries. when create .net standard library can referenced full framework classes, if version of .net standard using correct. sound confusing?

in simpler terms, take @ chart here https://github.com/dotnet/standard/blob/master/docs/versions.md

if full framework classes targeting .net framework 4.5, able use them in .net core 1.0, need make libraries use .net standard 1.1.

if have full framework web app running, , want build libraries in .net standard. reason should if..

• you intend convert webapp .net core in near future.
• you building class library may used in other .net core projects.

if sticking full framework web app foreseeable, there isn't need build things in .net standard (especially if having shoot cut down version of standard 1.1).

as why can't "target" framework when creating .net core project. it's known "bug" if will. or more dropdown redundant when creating .net core project. use latest version of .net core sdk on machine (by default).

further reading :

• .net standard vs .net core
• developing on 2 versions of .net core sdk