I do not understand the functionality of this plugin ...

[Avi Ziv]

I have a field in Project A and Project B.

For Project A: value1, value2, value3

For Project B: value1, value4, value5

Is it possible?

Because testing the plugin, I see definition in Project A affects also Project B  

[Nic Brough -Adaptavist- · Accepted solution]

You can do that without a plugin.  If you define a custom field of a select type, you can give it a different "context" for many projects.  So context 1 would give you value1, value2, value3 and you'd associate it with project A, and have a different context defined for project B

There's a couple of issues with doing that - the options are all separate and unique (in your lists you use value1 twice - you can use the same name in the two contexts, but JIRA has six separate options internally), and there are some issues around multiple contexts if you have fields that vary by project and issue type.

[Holger Schimanski]

The plugin Project Specific Select Field which is mentioned as a tag is only needed, if you want to provide project admins to be able to manage option values of these fields on their own. In standard JIRA the jira admin has to do this.