Constraints and Limitations

The following are basic constraints on using tags:

**Table 1** Constraints
Item	Specifications
Maximum number of key-value pairs you can add for each resource	10
Tags of each resource	For each resource, each tag key must be unique, and each tag key can have only one tag value.
Maximum number of predefined tags that you can create for an account	500
Predefined tags	If the created predefined tag is the same as an existing predefined tag, the existing predefined tag is overwritten. If only keys are the same and values are different, both the tags are available.
Tag keys	A tag key can contain a maximum of 36 characters, including digits, letters, underscores (_), and hyphens (-).
Tag values	A tag value can contain a maximum of 43 characters, including digits, letters, underscores (_), periods (.), and hyphens (-).