When a Tag is set to read only, a Lock icon is displayed next to the Tag in the Tag Browser.
Instead of making a tag Read Only for all users, you can conditionally provide read and write access based on Security Levels. Doing so involves a adjusting the security settings on the tag in question. The checkbox tree you are presented with will show you all of the security levels configured in the Gateway Config > Security > Security Levels page.
Read permissions define the security levels required in order to read values from a Tag. By default, Tags have Read Permissions set to "Public". You can change the Read security using the Tag Browser in the Designer.
Write permissions define the security levels required in order to write values a Tag. By default, Tags have Write Permissions set to "Public". You can change the Write security using the Tag Browser in the Designer.
Select the Security section.
If any security levels under the Read Permissions or Write Permissions sections are deleted from the Gateway, they will appear grayed-out with a red warning underline. A warning indicator icon will also appear in the upper right-hand corner with the number of selected security levels that no longer exist. If you follow the security levels tree up to the parent levels, you'll notice affected levels now include a dotted underline.
The deleted security level and all warning indications are removed when the deleted security level is unchecked and new settings are saved.
In addition to setting up security on individual Tags, you can set up security policies specific to Security Zones. This is useful in cases where you want to make all tags in a provider Read Only from network locations. See the Security Zones page for more details about Tag Access options.