What is a particular CMDB field for?Issue Documentation on what some fields in the CMDB are, and are for, or how they should be used, is not always there. This may be due to our developers considering this something you don't need to know, as custom implementations that used those fields were not envisaged, or maybe because fields are not used by any code and their purpose is lost in the mists of time. Or simply an oversight. This aims to fill some gaps or at least give steps to help you figure it out. Why do you need to know? You may be designing a custom implementation, and wonder if an OOTB field already exists for something you wantWhat class of CI is it relevant to?What code and features use the value as an input, where changing the value may change the behaviour of featuresWhat code and features may set the value automatically? Where you may find this out: Is it listed in the main documentation page for CMDB fields Configuration Item [cmdb_ci] classDoes the field have a description in the Dictionary / Is there a Hint in the label record for when hovering over the field label?Where is the hierarchy is it defined? e.g. computer, windows server, application, specific applicationWhich form layouts is it used on? The sys_ui_element table is a good starting point for that, and the Application Scope of the records may give the name of a feature.What package/application did the field get added by? CMDB, Discovery, patterns, CMDB, CSDM, service portfolio etc.Is it populated by discovery https://docs.servicenow.com/csh?topicname=r-discovery.html&version=latestIf you can't find anything anywhere, you might consider a support case as a last resort, so that our developers can be asked, and the documentation improved. If in doubt, don't re-use out-of-box fields for your own purposes. It is safer, and perfectly acceptable, to add your own custom fields to the CMDB. This will avoid your code impacting OOTB code, and vice versa. An example: The Dictionary record has these values Table: cmdb_ciName: monitorLabel: MonitorType: True/FalseHint: Enable monitoring of the configuration item Package: Configuration Management (CMDB) [com.snc.cmdb] The main CMDB field documentation page has:"Monitor - Indicates whether the instance is monitored" That's different. The "instance" of what? A search in the sys_ui_element table shows this field used in a "More Attributes" form section, and for a "CMDB Workspace application" view, and is used for many CI classes. Is this something to do with a "Monitor Instance", or for one of the internal monitoring plugins such as the Server-Side Monitoring for instance check-in (com.glide.instance_monitor) plugin? Was this something to do with the obsolete SNC Component [cmdb_ci_snc_component] class, which did used to have a CI for each ServiceNow instance node? Possibly. A quick scan through our current source code by the author doesn't appear to have any code related to it, but I can't be certain. For this particular field, it may be best to add your own custom field instead if you need a checkbox related to whether the CI is to be monitored or not. It would certainly be safer, and quicker.