User rights are normally used when you have multiple matrices linked (trunked) together in a facility
example , where you may have a MCR matrix , Studio 1 matrix , Studio 2 matrix, Studio 3 matrix and a News Matrix etc..
Each technical engineer for each studio will want to access and edit the configurations t configuration related to their matrix at any one time without disturbing the other technical engineers in the other studios. However we want to ensure , that no studio engineer breaks the trunks lines interconnecting the matrices when they edit their map
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If no network admin is logged in then you can have multiple local admins or Users  logged intoin
They can only log into the matrices they have access to
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Once a matrix is being edited all other admin / users that have write access are locked out including the Network Admin user from that specific matrix
see other related FAQs EHX local Admin restrictions