CfnOrganizationConfigRule
- class aws_cdk.aws_config.CfnOrganizationConfigRule(scope, id, *, organization_config_rule_name, excluded_accounts=None, organization_custom_policy_rule_metadata=None, organization_custom_rule_metadata=None, organization_managed_rule_metadata=None)
Bases:
CfnResource
A CloudFormation
AWS::Config::OrganizationConfigRule
.Adds or updates an AWS Config rule for your entire organization to evaluate if your AWS resources comply with your desired configurations. For information on how many organization AWS Config rules you can have per account, see *Service Limits* in the AWS Config Developer Guide .
Only a management account and a delegated administrator can create or update an organization AWS Config rule. When calling the
OrganizationConfigRule
resource with a delegated administrator, you must ensure AWS OrganizationsListDelegatedAdministrator
permissions are added. An organization can have up to 3 delegated administrators.The
OrganizationConfigRule
resource enables organization service access through theEnableAWSServiceAccess
action and creates a service-linked roleAWSServiceRoleForConfigMultiAccountSetup
in the management or delegated administrator account of your organization. The service-linked role is created only when the role does not exist in the caller account. AWS Config verifies the existence of role withGetRole
action.To use the
OrganizationConfigRule
resource with delegated administrator, register a delegated administrator by calling AWS Organizationregister-delegated-administrator
forconfig-multiaccountsetup.amazonaws.com
.There are two types of rules: AWS Config Managed Rules and AWS Config Custom Rules . You can use
PutOrganizationConfigRule
to create both AWS Config Managed Rules and AWS Config Custom Rules.AWS Config Managed Rules are predefined, customizable rules created by AWS Config . For a list of managed rules, see List of AWS Config Managed Rules . If you are adding an AWS Config managed rule, you must specify the rule’s identifier for the
RuleIdentifier
key.AWS Config Custom Rules are rules that you create from scratch. There are two ways to create AWS Config custom rules: with Lambda functions ( AWS Lambda Developer Guide ) and with Guard ( Guard GitHub Repository ), a policy-as-code language. AWS Config custom rules created with AWS Lambda are called AWS Config Custom Lambda Rules and AWS Config custom rules created with Guard are called AWS Config Custom Policy Rules .
If you are adding a new AWS Config Custom Lambda rule, you first need to create an AWS Lambda function in the management account or a delegated administrator that the rule invokes to evaluate your resources. You also need to create an IAM role in the managed account that can be assumed by the Lambda function. When you use
PutOrganizationConfigRule
to add a Custom Lambda rule to AWS Config , you must specify the Amazon Resource Name (ARN) that AWS Lambda assigns to the function.- CloudformationResource:
AWS::Config::OrganizationConfigRule
- Link:
- ExampleMetadata:
fixture=_generated
Example:
# The code below shows an example of how to instantiate this type. # The values are placeholders you should change. import aws_cdk.aws_config as config cfn_organization_config_rule = config.CfnOrganizationConfigRule(self, "MyCfnOrganizationConfigRule", organization_config_rule_name="organizationConfigRuleName", # the properties below are optional excluded_accounts=["excludedAccounts"], organization_custom_policy_rule_metadata=config.CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty( policy_text="policyText", runtime="runtime", # the properties below are optional debug_log_delivery_accounts=["debugLogDeliveryAccounts"], description="description", input_parameters="inputParameters", maximum_execution_frequency="maximumExecutionFrequency", organization_config_rule_trigger_types=["organizationConfigRuleTriggerTypes"], resource_id_scope="resourceIdScope", resource_types_scope=["resourceTypesScope"], tag_key_scope="tagKeyScope", tag_value_scope="tagValueScope" ), organization_custom_rule_metadata=config.CfnOrganizationConfigRule.OrganizationCustomRuleMetadataProperty( lambda_function_arn="lambdaFunctionArn", organization_config_rule_trigger_types=["organizationConfigRuleTriggerTypes"], # the properties below are optional description="description", input_parameters="inputParameters", maximum_execution_frequency="maximumExecutionFrequency", resource_id_scope="resourceIdScope", resource_types_scope=["resourceTypesScope"], tag_key_scope="tagKeyScope", tag_value_scope="tagValueScope" ), organization_managed_rule_metadata=config.CfnOrganizationConfigRule.OrganizationManagedRuleMetadataProperty( rule_identifier="ruleIdentifier", # the properties below are optional description="description", input_parameters="inputParameters", maximum_execution_frequency="maximumExecutionFrequency", resource_id_scope="resourceIdScope", resource_types_scope=["resourceTypesScope"], tag_key_scope="tagKeyScope", tag_value_scope="tagValueScope" ) )
Create a new
AWS::Config::OrganizationConfigRule
.- Parameters:
scope (
Construct
) –scope in which this resource is defined.
id (
str
) –scoped id of the resource.
organization_config_rule_name (
str
) – The name that you assign to organization AWS Config rule.excluded_accounts (
Optional
[Sequence
[str
]]) – A comma-separated list of accounts excluded from organization AWS Config rule.organization_custom_policy_rule_metadata (
Union
[IResolvable
,OrganizationCustomPolicyRuleMetadataProperty
,Dict
[str
,Any
],None
]) –AWS::Config::OrganizationConfigRule.OrganizationCustomPolicyRuleMetadata
.organization_custom_rule_metadata (
Union
[IResolvable
,OrganizationCustomRuleMetadataProperty
,Dict
[str
,Any
],None
]) – AnOrganizationCustomRuleMetadata
object.organization_managed_rule_metadata (
Union
[IResolvable
,OrganizationManagedRuleMetadataProperty
,Dict
[str
,Any
],None
]) – AnOrganizationManagedRuleMetadata
object.
Methods
- add_deletion_override(path)
Syntactic sugar for
addOverride(path, undefined)
.- Parameters:
path (
str
) – The path of the value to delete.- Return type:
None
- add_depends_on(target)
Indicates that this resource depends on another resource and cannot be provisioned unless the other resource has been successfully provisioned.
This can be used for resources across stacks (or nested stack) boundaries and the dependency will automatically be transferred to the relevant scope.
- Parameters:
target (
CfnResource
) –- Return type:
None
- add_metadata(key, value)
Add a value to the CloudFormation Resource Metadata.
- Parameters:
key (
str
) –value (
Any
) –
- See:
- Return type:
None
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/metadata-section-structure.html
Note that this is a different set of metadata from CDK node metadata; this metadata ends up in the stack template under the resource, whereas CDK node metadata ends up in the Cloud Assembly.
- add_override(path, value)
Adds an override to the synthesized CloudFormation resource.
To add a property override, either use
addPropertyOverride
or prefixpath
with “Properties.” (i.e.Properties.TopicName
).If the override is nested, separate each nested level using a dot (.) in the path parameter. If there is an array as part of the nesting, specify the index in the path.
To include a literal
.
in the property name, prefix with a\
. In most programming languages you will need to write this as"\\."
because the\
itself will need to be escaped.For example:
cfn_resource.add_override("Properties.GlobalSecondaryIndexes.0.Projection.NonKeyAttributes", ["myattribute"]) cfn_resource.add_override("Properties.GlobalSecondaryIndexes.1.ProjectionType", "INCLUDE")
would add the overrides Example:
"Properties": { "GlobalSecondaryIndexes": [ { "Projection": { "NonKeyAttributes": [ "myattribute" ] ... } ... }, { "ProjectionType": "INCLUDE" ... }, ] ... }
The
value
argument toaddOverride
will not be processed or translated in any way. Pass raw JSON values in here with the correct capitalization for CloudFormation. If you pass CDK classes or structs, they will be rendered with lowercased key names, and CloudFormation will reject the template.- Parameters:
path (
str
) –The path of the property, you can use dot notation to override values in complex types. Any intermdediate keys will be created as needed.
value (
Any
) –The value. Could be primitive or complex.
- Return type:
None
- add_property_deletion_override(property_path)
Adds an override that deletes the value of a property from the resource definition.
- Parameters:
property_path (
str
) – The path to the property.- Return type:
None
- add_property_override(property_path, value)
Adds an override to a resource property.
Syntactic sugar for
addOverride("Properties.<...>", value)
.- Parameters:
property_path (
str
) – The path of the property.value (
Any
) – The value.
- Return type:
None
- apply_removal_policy(policy=None, *, apply_to_update_replace_policy=None, default=None)
Sets the deletion policy of the resource based on the removal policy specified.
The Removal Policy controls what happens to this resource when it stops being managed by CloudFormation, either because you’ve removed it from the CDK application or because you’ve made a change that requires the resource to be replaced.
The resource can be deleted (
RemovalPolicy.DESTROY
), or left in your AWS account for data recovery and cleanup later (RemovalPolicy.RETAIN
).- Parameters:
policy (
Optional
[RemovalPolicy
]) –apply_to_update_replace_policy (
Optional
[bool
]) – Apply the same deletion policy to the resource’s “UpdateReplacePolicy”. Default: truedefault (
Optional
[RemovalPolicy
]) – The default policy to apply in case the removal policy is not defined. Default: - Default value is resource specific. To determine the default value for a resoure, please consult that specific resource’s documentation.
- Return type:
None
- get_att(attribute_name)
Returns a token for an runtime attribute of this resource.
Ideally, use generated attribute accessors (e.g.
resource.arn
), but this can be used for future compatibility in case there is no generated attribute.- Parameters:
attribute_name (
str
) – The name of the attribute.- Return type:
- get_metadata(key)
Retrieve a value value from the CloudFormation Resource Metadata.
- Parameters:
key (
str
) –- See:
- Return type:
Any
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/metadata-section-structure.html
Note that this is a different set of metadata from CDK node metadata; this metadata ends up in the stack template under the resource, whereas CDK node metadata ends up in the Cloud Assembly.
- inspect(inspector)
Examines the CloudFormation resource and discloses attributes.
- Parameters:
inspector (
TreeInspector
) –tree inspector to collect and process attributes.
- Return type:
None
- override_logical_id(new_logical_id)
Overrides the auto-generated logical ID with a specific ID.
- Parameters:
new_logical_id (
str
) – The new logical ID to use for this stack element.- Return type:
None
- to_string()
Returns a string representation of this construct.
- Return type:
str
- Returns:
a string representation of this resource
Attributes
- CFN_RESOURCE_TYPE_NAME = 'AWS::Config::OrganizationConfigRule'
- cfn_options
Options for this resource, such as condition, update policy etc.
- cfn_resource_type
AWS resource type.
- creation_stack
return:
the stack trace of the point where this Resource was created from, sourced from the +metadata+ entry typed +aws:cdk:logicalId+, and with the bottom-most node +internal+ entries filtered.
- excluded_accounts
A comma-separated list of accounts excluded from organization AWS Config rule.
- logical_id
The logical ID for this CloudFormation stack element.
The logical ID of the element is calculated from the path of the resource node in the construct tree.
To override this value, use
overrideLogicalId(newLogicalId)
.- Returns:
the logical ID as a stringified token. This value will only get resolved during synthesis.
- node
The construct tree node associated with this construct.
- organization_config_rule_name
The name that you assign to organization AWS Config rule.
- organization_custom_policy_rule_metadata
AWS::Config::OrganizationConfigRule.OrganizationCustomPolicyRuleMetadata
.
- organization_custom_rule_metadata
An
OrganizationCustomRuleMetadata
object.
- organization_managed_rule_metadata
An
OrganizationManagedRuleMetadata
object.
- ref
Return a string that will be resolved to a CloudFormation
{ Ref }
for this element.If, by any chance, the intrinsic reference of a resource is not a string, you could coerce it to an IResolvable through
Lazy.any({ produce: resource.ref })
.
- stack
The stack in which this element is defined.
CfnElements must be defined within a stack scope (directly or indirectly).
Static Methods
- classmethod is_cfn_element(x)
Returns
true
if a construct is a stack element (i.e. part of the synthesized cloudformation template).Uses duck-typing instead of
instanceof
to allow stack elements from different versions of this library to be included in the same stack.- Parameters:
x (
Any
) –- Return type:
bool
- Returns:
The construct as a stack element or undefined if it is not a stack element.
- classmethod is_cfn_resource(construct)
Check whether the given construct is a CfnResource.
- Parameters:
construct (
IConstruct
) –- Return type:
bool
- classmethod is_construct(x)
Return whether the given object is a Construct.
- Parameters:
x (
Any
) –- Return type:
bool
OrganizationCustomPolicyRuleMetadataProperty
- class CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty(*, policy_text, runtime, debug_log_delivery_accounts=None, description=None, input_parameters=None, maximum_execution_frequency=None, organization_config_rule_trigger_types=None, resource_id_scope=None, resource_types_scope=None, tag_key_scope=None, tag_value_scope=None)
Bases:
object
- Parameters:
policy_text (
str
) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.PolicyText
.runtime (
str
) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.Runtime
.debug_log_delivery_accounts (
Optional
[Sequence
[str
]]) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.DebugLogDeliveryAccounts
.description (
Optional
[str
]) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.Description
.input_parameters (
Optional
[str
]) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.InputParameters
.maximum_execution_frequency (
Optional
[str
]) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.MaximumExecutionFrequency
.organization_config_rule_trigger_types (
Optional
[Sequence
[str
]]) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.OrganizationConfigRuleTriggerTypes
.resource_id_scope (
Optional
[str
]) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.ResourceIdScope
.resource_types_scope (
Optional
[Sequence
[str
]]) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.ResourceTypesScope
.tag_key_scope (
Optional
[str
]) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.TagKeyScope
.tag_value_scope (
Optional
[str
]) –CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.TagValueScope
.
- Link:
- ExampleMetadata:
fixture=_generated
Example:
# The code below shows an example of how to instantiate this type. # The values are placeholders you should change. import aws_cdk.aws_config as config organization_custom_policy_rule_metadata_property = config.CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty( policy_text="policyText", runtime="runtime", # the properties below are optional debug_log_delivery_accounts=["debugLogDeliveryAccounts"], description="description", input_parameters="inputParameters", maximum_execution_frequency="maximumExecutionFrequency", organization_config_rule_trigger_types=["organizationConfigRuleTriggerTypes"], resource_id_scope="resourceIdScope", resource_types_scope=["resourceTypesScope"], tag_key_scope="tagKeyScope", tag_value_scope="tagValueScope" )
Attributes
- debug_log_delivery_accounts
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.DebugLogDeliveryAccounts
.
- description
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.Description
.
- input_parameters
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.InputParameters
.
- maximum_execution_frequency
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.MaximumExecutionFrequency
.
- organization_config_rule_trigger_types
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.OrganizationConfigRuleTriggerTypes
.
- policy_text
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.PolicyText
.
- resource_id_scope
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.ResourceIdScope
.
- resource_types_scope
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.ResourceTypesScope
.
- runtime
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.Runtime
.
- tag_key_scope
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.TagKeyScope
.
- tag_value_scope
CfnOrganizationConfigRule.OrganizationCustomPolicyRuleMetadataProperty.TagValueScope
.
OrganizationCustomRuleMetadataProperty
- class CfnOrganizationConfigRule.OrganizationCustomRuleMetadataProperty(*, lambda_function_arn, organization_config_rule_trigger_types, description=None, input_parameters=None, maximum_execution_frequency=None, resource_id_scope=None, resource_types_scope=None, tag_key_scope=None, tag_value_scope=None)
Bases:
object
organization custom rule metadata such as resource type, resource ID of AWS resource, Lambda function ARN, and organization trigger types that trigger AWS Config to evaluate your AWS resources against a rule.
It also provides the frequency with which you want AWS Config to run evaluations for the rule if the trigger type is periodic.
- Parameters:
lambda_function_arn (
str
) – The lambda function ARN.organization_config_rule_trigger_types (
Sequence
[str
]) – The type of notification that triggers AWS Config to run an evaluation for a rule. You can specify the following notification types: -ConfigurationItemChangeNotification
- Triggers an evaluation when AWS Config delivers a configuration item as a result of a resource change. -OversizedConfigurationItemChangeNotification
- Triggers an evaluation when AWS Config delivers an oversized configuration item. AWS Config may generate this notification type when a resource changes and the notification exceeds the maximum size allowed by Amazon SNS. -ScheduledNotification
- Triggers a periodic evaluation at the frequency specified forMaximumExecutionFrequency
.description (
Optional
[str
]) – The description that you provide for your organization AWS Config rule.input_parameters (
Optional
[str
]) – A string, in JSON format, that is passed to your organization AWS Config rule Lambda function.maximum_execution_frequency (
Optional
[str
]) – The maximum frequency with which AWS Config runs evaluations for a rule. Your custom rule is triggered when AWS Config delivers the configuration snapshot. For more information, seeConfigSnapshotDeliveryProperties
. .. epigraph:: By default, rules with a periodic trigger are evaluated every 24 hours. To change the frequency, specify a valid value for theMaximumExecutionFrequency
parameter.resource_id_scope (
Optional
[str
]) – The ID of the AWS resource that was evaluated.resource_types_scope (
Optional
[Sequence
[str
]]) – The type of the AWS resource that was evaluated.tag_key_scope (
Optional
[str
]) – One part of a key-value pair that make up a tag. A key is a general label that acts like a category for more specific tag values.tag_value_scope (
Optional
[str
]) – The optional part of a key-value pair that make up a tag. A value acts as a descriptor within a tag category (key).
- Link:
- ExampleMetadata:
fixture=_generated
Example:
# The code below shows an example of how to instantiate this type. # The values are placeholders you should change. import aws_cdk.aws_config as config organization_custom_rule_metadata_property = config.CfnOrganizationConfigRule.OrganizationCustomRuleMetadataProperty( lambda_function_arn="lambdaFunctionArn", organization_config_rule_trigger_types=["organizationConfigRuleTriggerTypes"], # the properties below are optional description="description", input_parameters="inputParameters", maximum_execution_frequency="maximumExecutionFrequency", resource_id_scope="resourceIdScope", resource_types_scope=["resourceTypesScope"], tag_key_scope="tagKeyScope", tag_value_scope="tagValueScope" )
Attributes
- description
The description that you provide for your organization AWS Config rule.
- input_parameters
A string, in JSON format, that is passed to your organization AWS Config rule Lambda function.
- lambda_function_arn
The lambda function ARN.
- maximum_execution_frequency
The maximum frequency with which AWS Config runs evaluations for a rule.
Your custom rule is triggered when AWS Config delivers the configuration snapshot. For more information, see
ConfigSnapshotDeliveryProperties
. .. epigraph:By default, rules with a periodic trigger are evaluated every 24 hours. To change the frequency, specify a valid value for the ``MaximumExecutionFrequency`` parameter.
- organization_config_rule_trigger_types
The type of notification that triggers AWS Config to run an evaluation for a rule.
You can specify the following notification types:
ConfigurationItemChangeNotification
- Triggers an evaluation when AWS Config delivers a configuration item as a result of a resource change.OversizedConfigurationItemChangeNotification
- Triggers an evaluation when AWS Config delivers an oversized configuration item. AWS Config may generate this notification type when a resource changes and the notification exceeds the maximum size allowed by Amazon SNS.ScheduledNotification
- Triggers a periodic evaluation at the frequency specified forMaximumExecutionFrequency
.
- resource_id_scope
The ID of the AWS resource that was evaluated.
- resource_types_scope
The type of the AWS resource that was evaluated.
- tag_key_scope
One part of a key-value pair that make up a tag.
A key is a general label that acts like a category for more specific tag values.
- tag_value_scope
The optional part of a key-value pair that make up a tag.
A value acts as a descriptor within a tag category (key).
OrganizationManagedRuleMetadataProperty
- class CfnOrganizationConfigRule.OrganizationManagedRuleMetadataProperty(*, rule_identifier, description=None, input_parameters=None, maximum_execution_frequency=None, resource_id_scope=None, resource_types_scope=None, tag_key_scope=None, tag_value_scope=None)
Bases:
object
organization managed rule metadata such as resource type and ID of AWS resource along with the rule identifier.
It also provides the frequency with which you want AWS Config to run evaluations for the rule if the trigger type is periodic.
- Parameters:
rule_identifier (
str
) – For organization config managed rules, a predefined identifier from a list. For example,IAM_PASSWORD_POLICY
is a managed rule. To reference a managed rule, see Using AWS Config managed rules .description (
Optional
[str
]) – The description that you provide for your organization AWS Config rule.input_parameters (
Optional
[str
]) – A string, in JSON format, that is passed to your organization AWS Config rule Lambda function.maximum_execution_frequency (
Optional
[str
]) – The maximum frequency with which AWS Config runs evaluations for a rule. This is for an AWS Config managed rule that is triggered at a periodic frequency. .. epigraph:: By default, rules with a periodic trigger are evaluated every 24 hours. To change the frequency, specify a valid value for theMaximumExecutionFrequency
parameter.resource_id_scope (
Optional
[str
]) – The ID of the AWS resource that was evaluated.resource_types_scope (
Optional
[Sequence
[str
]]) – The type of the AWS resource that was evaluated.tag_key_scope (
Optional
[str
]) – One part of a key-value pair that make up a tag. A key is a general label that acts like a category for more specific tag values.tag_value_scope (
Optional
[str
]) – The optional part of a key-value pair that make up a tag. A value acts as a descriptor within a tag category (key).
- Link:
- ExampleMetadata:
fixture=_generated
Example:
# The code below shows an example of how to instantiate this type. # The values are placeholders you should change. import aws_cdk.aws_config as config organization_managed_rule_metadata_property = config.CfnOrganizationConfigRule.OrganizationManagedRuleMetadataProperty( rule_identifier="ruleIdentifier", # the properties below are optional description="description", input_parameters="inputParameters", maximum_execution_frequency="maximumExecutionFrequency", resource_id_scope="resourceIdScope", resource_types_scope=["resourceTypesScope"], tag_key_scope="tagKeyScope", tag_value_scope="tagValueScope" )
Attributes
- description
The description that you provide for your organization AWS Config rule.
- input_parameters
A string, in JSON format, that is passed to your organization AWS Config rule Lambda function.
- maximum_execution_frequency
The maximum frequency with which AWS Config runs evaluations for a rule.
This is for an AWS Config managed rule that is triggered at a periodic frequency. .. epigraph:
By default, rules with a periodic trigger are evaluated every 24 hours. To change the frequency, specify a valid value for the ``MaximumExecutionFrequency`` parameter.
- resource_id_scope
The ID of the AWS resource that was evaluated.
- resource_types_scope
The type of the AWS resource that was evaluated.
- rule_identifier
For organization config managed rules, a predefined identifier from a list.
For example,
IAM_PASSWORD_POLICY
is a managed rule. To reference a managed rule, see Using AWS Config managed rules .
- tag_key_scope
One part of a key-value pair that make up a tag.
A key is a general label that acts like a category for more specific tag values.
- tag_value_scope
The optional part of a key-value pair that make up a tag.
A value acts as a descriptor within a tag category (key).