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9. Access Control and Capability Grant Language

Access rules, capability grants, and obligations are explained in Data Access Conditions, this document specifies the precise syntax and values that can be used.

An access rule contains:

  1. Zero or more conditions for access

  2. One or more capability grants to the data consumer if access is granted

  3. Zero or more obligations falling on the data consumer if access is granted

They are applied to properties of a Data Consumer while processing a request for data from a Data Provider. These properties can be modelled as a map of names to values; some values may be inferred by joining on the ID of the data consumer, some may be directly provided in the Token introspection response.

9.1. Syntax

9.1.1. Names

Names consist of a namespace ([a-z0-9_]+), a : character, and a suffix ([a-z0-9_.]+). For example, oe:some_value. Values asserted by Open Energy will always have a namespace oe. The suffix may contain . characters, the namespace may not.

9.1.2. Rule syntax

An access rule is represented as a single line string containing a comma separated list of zero or more Conditions, the literal string grants, and then a comma separated list of one or more Capabilities. Optionally, this may be followed by the literal requires and one or more Obligations in a comma separated list.



  • A rule with no conditions is valid, and is satisfied by all requests

  • All rules must grant at least one capability

  • Rules may have zero or more obligations

See the following sections for specification of conditions and capabilities.

9.2. Conditions

Conditions are unary or binary clauses.

All conditions must be satisfied within a rule for that rule to be applied. There are no explicit boolean operators such as or or similar. For cases where alternative sets of rules could be applied the expectation is that data providers will specify multiple, potentially overlapping, rules to express this.

9.2.1. Unary clauses

Unary clauses consist of a single named condition. The clause is satisfied if that condition is true. This is typically used to denote a particular property such as Open Energy current membership or similar where the existence of the property is sufficient to accept the data consumer.

Listing 9.1 the condition oe:member passes if used with this context
 {"oe:member" : true}

9.2.2. Binary clauses

Binary clauses consist of a name on the left hand side, an operator, and a value on the right hand side. The valid operators are shown in the table below. LHS, operator, and RHS are separated with at least one space character.

Values can be numerals, dates, quoted strings, or homogeneous lists of these three types. Dates are specified as dd/mm/yyyy, we do not need a higher level of precision in any of our envisaged use cases, but if this is needed a datetime must be specified as a string compliant with RFC3339. To simplify expression in JSON, quoted strings should be enclosed in single quote ' characters. Lists are written as a comma separated list of strings surrounded by [ and ] characters. Lists are only valid RHS values for the in operator.

Table 9.1 Operators






The condition passes if the value of the property on the LHS is exactly equal to the value in the RHS


date or datetime

The condition passes if the value of the property on the LHS is before the date or datetime specifed as the RHS. Where a date needs to be coerced to a datetime, it is done by setting it to 00:00.00 with the same date


date or datetime

As above, but passes if the value of the property on the LHS is after the date or datetime specified on the RHS.


date or datetime

The condition passes if the value on the LHS corresponds to a date at most X days in the past compared to the current date, where X is integer numeral specified as the RHS

<, <=, >=, >, ==


Conditions pass if the LHS is, respectively, less than, less than or equal, greater than or equal, greater than, or strictly equal, to the number on the RHS. Note that == and is are equivalent for numeric quantities


number or string

Conditions pass if there is at least one item in the list specified in the RHS which would match the is condition with respect to the LHS value

9.2.3. Example conditions


The conditions shown below are examples, and should not be taken as indicative of standard properties of data consumers in the final system.

Table 9.2 Example condition clauses



oe:status is 'active'

passes if the value of oe:status is set, and is equal under string comparison to active

oe:membership_expires after 24/10/2022

passes if the value of oe:membership_expires is either a date or a datetime, and is after the 24th October 2022

oe:terms_signed max_age_days 20

passes if the value of oe:terms_signed is either a date or a datetime, and is at most 20 days from the current datetime. Note that dates with no time component are equivalent to 00:00.00 on the specified date for comparison purposes

some_group:membership_level >= 2

passes if the value of some_group:membership_level is a number and is greater to or equal to two.

oe:org_type in ['council', 'academic']

passes if the value of oe:org_type would be considered equal to either 'council' or 'academic' as if compared with is.


passes if the value of oe:member is true.

9.2.4. Specifying multiple conditions

Multiple conditions are separated with , characters. All conditions must be satisfied for the rule to pass, there are no sub-clauses or boolean operators. Any number of space characters are allowed before and after the , in a condition list.

For example, oe:status is 'active', some_group:membership_level >=2 is the union of those two example conditions from the previous section and will only be satisfied if both conditions are individually satisfiable.

9.3. Capabilities

Capability grants for a given set of access conditions are specified as a comma (,) separated list of names. There MUST be at least one name in this list, an empty capability grant list is not considered valid.

9.3.1. Standard capabilities

These are capabilities where the namespace part of the name is oe, indicating that they are defined as part of the open energy project. Data providers SHOULD NOT, create their own capabilities unless absolutely necessary as doing so acts against the aim of easy interoperability and comprehension of access and licensing rules.

Any additional capabilities designed MUST be prefixed with the organisation ID of the data provider responsible for their definition, and any such data provider MUST publish a clear, legally valid, definition of any such capabilities. In addition, data providers creating custom capabilities MUST inform the OEGS of this, providing links to the aforementioned documentation.


This section is provisional, the exact final set of base capabilities has yet to be determined. Those shown below are a plausible first cut but should not be considered definitive.

Table 9.3 Standard capabilities


Capability name



Use the artefact internally


For any purpose


For development purposes only (i.e. private or limited development of new works, products or services)


For non-commercial purposes only (e.g. education, research, charity work etc.)


Adapt the artefact for internal use


For any purpose


For development purposes only (i.e. private or limited development of new works, products or services)


For non-commercial purposes only (e.g. education, research, charity work etc.)


Combine (‘remix’) the artefact


With any other artefacts


With other external artefacts


With the Data Consumer’s own products or services


Redistribute (‘onward share’ - including to any customers of the Service Provider)


The original artefact


Derivatives of the original artefact not produced from other data sets, i.e. filtered or cleaned data


Derivatives of the artefact produced through artefact combination or use in the Data Consumer’s own products or services

9.3.2. Expressing Open Data licenses with capabilities

The capabilities defined above in Standard capabilities are intended for shared data, but data providers may also publish open data. An open data set by definition has no access conditions, so any access rules for such data sets MUST have an empty access condition list, and must use one of the following capabilities to declare that the data are licensed under a known OSI approved open license

Rules MUST NOT grant a mix of capabilities in the open namespace and capabilities in other namespaces, as the semantics of this are not well defined.

Capability name

Corresponding open data license

open:cc_by_1.0 open:cc_by_2.0 open:cc_by_2.5 open:cc_by_3.0 open:cc_by_4.0

Creative Commons Attribution (v1.0, v2.0, v2.5, v3.0, v4.0 respectively)

open:cc_by_sa_1.0 open:cc_by_sa_2.0 open:cc_by_sa_2.5 open:cc_by_sa_3.0 open:cc_by_sa_4.0

Creative Commons Attribution ShareAlike (v1.0, v2.0, v2.5, v3.0, v4.0 respectively)


Public Domain Dedication v1.0

open:gfdl_1.1 open:gfdl_1.2 open:gfdl_1.3

GNU Free Documentation License (v1.1, 1.2, 1.3 respectively)

open:fal_1.2 open:fal1.3

Free Art License (v1.2, v1.3 respectively)

Open data sets SHOULD be released under the latest version of any given license.

9.4. Obligations

Obligations are constraints on what the data consumer can do with the data, restricting or specialising the capabilities granted. They are specified as a single name.

9.4.1. Standard obligations


This set of standard obligations is provisional and may be subject to change

Table 9.4 Standard obligations






Re-users must display the full text of the license every time they use the work



Re-users must attribute the work to the original source when they use it



Re-users who create derivatives of the work must release the derivatives under the same license as the original work, if they choose to distribute the derivatives


Two additional common constraints in existing (mostly open) licenses are NonCommercial and NoDerivatives. These are explicitly not included here as it is possible to express this through the access conditions (i.e. rather than declaring that a data set is only available for non-commercial usage it is better to say that only non-commercial entities may access it). This is not quite equivalent, but simpler and better defined than the relative minefield of defining ‘non commercial use’.