What should be included in the referendum question?

Legal Regime governing Referenda (Law no. 15-A/98 of 3 April 1998, last amended by Organic Law no. 3/2017 of 18 July 2017)

Article 12: Discussion and voting

2 – Resolutions that are to be put to the vote by the Plenary of the Assembly of the Republic shall include the questions that are to be formulated and the definition of the electoral universe that is to be consulted.

Article 17: Form

1 – Popular initiatives shall be submitted in writing, on paper or by electronic means, shall be addressed to the Assembly of the Republic, and shall contain the signatories’ identity details, to comprise the full name, identity card or citizen’s card number, electoral number and date of birth of each one. […]

6 – The initiative shall contain the precise text of the question or questions to be submitted to referendum and the grounds for it or them, to be duly accompanied by a list of the acts that are currently under consideration at the Assembly of the Republic.

Article 23: Competence, form and publication

1 – The Council of Ministers has the competence to approve draft government referenda.

2 – Drafts shall take the form of a Council of Ministers resolution published in Series I-A of the Diário da República.

Article 24: Content of resolutions

The Council of Ministers resolution shall include the questions that are to be formulated and the definition of the electoral universe that is to be consulted.

The legislation is not entirely clear in this regard. Reading the Article 17.2 it can be assumed that the explanatory text for the referendum question is one of the requirements.