Tcode me28 user id wise supplier plant restriction.

ME28 is a legacy transaction (meaning it predates S4HANA, and determination volition be no further codefixes / modifications oregon different from SAP Development), this is extracurricular of SAP's enactment scope. 

In short, it is not imaginable to modify ME28 arsenic the connection operation is filled from a tract awesome that is assigned based connected tract of programme SAPLMEPO, this volition not enactment successful ME28, lone successful ME29N.

The crushed is that successful ME28, SAPLMEPO is not called, alternatively SAPMM06E is used. 

This means that adjacent if issues successful modular codification are recovered successful ME28, no further updates oregon fixes are provided by SAP.

While the transaction is inactive disposable for usage connected your ain risk, SAP proposal is to usage ME29N lone (single release) as this supports aboriginal functionality based astir SAPLMEPO (and not the bequest relation SAPMM06E.

Note besides that determination are nary idiosyncratic exits / BADIs tin beryllium utilized to instrumentality customized logic either - which, with the payment of hindsight, this and different factors looks to person contributed to the determination to halt further improvement successful this country erstwhile the "N" / Enjoy based transactions were archetypal introduced.

I anticipation this explains the strategy behaviour astir bequest transactions specified arsenic this, acknowledgment for the question!