The OIDC Provider from BankID supports two general classes of Access Tokens. 

• By-reference in terms of standard Bearer Tokens. Tokens of this kind comes with corresponding support for Introspection to determine the Authorization Context for any particular token value.
• Self-contained in terms JSON WebTokens (JWT) that are signed (JWS) and optionally also encrypted (JWE). Tokens of this kind contain all required information to determine the Authorization Context.

The Authorization Context of an Access Token referes to attributes such as:

• The issuer (iss)of the access token. See corresponding claim in ID Token.
• The subject identifier (sub) of the access token, ie. a reference to the end-user (resource owner) that authorized the access token. See corresponding claim in ID Token.
• Intended audience (aud)for the access token, ie. a reference to the Protected Resouce that the access token regulates access to. Note that this is not related to the corresponding claim in the ID Token. The audience for the ID Token (being the OIDC Client) is different from the audience for an Access Token (being the Resource Server in question). 
• Active state / expiry (exp)of the access token
• The specific set of scopes and claims associated with the access token, ie. the set included in the Authorize request that subsequently resulted in the issuance of the Access Token in a reponse to a Token request

The OIDC Provider issues different types of Access Tokens to OIDC Clients depending on the requested types of Protected Resources (as given by the Scopes and Claims contained in the request). The OIDC Provider supports 

The default type of Access Token, which is used by the TINFO (Userinfo) service, is a standard Bearer Token that is general.   is not associated with any particular value for the audience (aud) attribute.

be used by any Protected Resource. Hence, the default token audience (aud) 

 Each particular type of Access Token is associated with a Supplementary Services as described separately:

• The TINFO (Userinfo) service uses a standard by-reference token of the bearer type.
• The PSD2 Service involves a set of non-standard tokens, including both by-reference tokens and by-value tokens.