Review Comment:
This article provides a comprehensive framework for evaluating CH semantic portals with a focus on increasing the implementation of interoperable Semantic Web applications for cultural heritage. The article provides an interesting overview and is interesting to the broader Semantic Web community. While the article is well structured, I am providing a list of suggestions and minor comments.
## Abstract
- After reading the text, they use PRISMA for the analysis. In this sense, the abstract could be improved by mentioning that PRISMA was employed as main framework?
- The abstract could also briefly describe future work.
### Section 1 Introduction
- The introduction could be enhanced by describing current initiatives concerning the publication and reuse of digital collections such as AI4LAM, GLAM Labs, CARE and Collections as data. The authors will find many references with regard to these international initiatives.
- I would suggest clearly stating the audience of this work (e.g., targeted at researchers, PhD students, practitioners...)
- A potential reference to be included: Toma Tasovac, Sally Chambers, Erzsébet Tóth-Czifra. Cultural Heritage Data from a Humanities Research Perspective: A DARIAH Position Paper. 2020. ⟨hal-02961317⟩
### Section 2
- In Section 2.1, I miss Wikibase, and in particular Wikibase Cloud (https://www.wikibase.cloud/), as a semantic portal to publish and enrich digital collections.
### Section 3.
- The authors state that they use PRISMA, however, I would suggest to provide an overview of "similar" techniques and to state why they use PRISMA.
- The authors provide RQ1-RQ5 for the analysis. The questions are of interest for the community. If possible, I would suggest improving these with additional topics such as the use of AI in combination with the semantic portals as well as the integration with data research infrastructures such as data spaces (https://www.dataspace-culturalheritage.eu/en) o cloud infrastructures (https://www.echoes-eccch.eu/). While I understand that these infrastructures are still underdevelopment, and analysis and/or brief description could help institutions and projects to engage with them. This will also increase the impact and visibility of this work.
### Section 4 Results
- When the authors mention that the data is connected to external repositories such as Wikidata, it might be worth it mentioning that in many cases this link is done via a Wikidata property instead of an owl:sameAs property.
### Section 5 Discussion
- The authors could use the acronym for cultural heritage since they previously provided the extended text. Please, review all the acronyms so they follow a similar scheme (1st time they appear extended and acronym, then the rest of the appearances use the acronym)
### Conclusions
- A potential idea for future work to improve this work could be to publish the results in the form of Collections as data and/or using a semantic vocabulary/ontology to describe the results.
- machine-readeble -> machine-readable
### General
- The authors use "Fig", "fig." and "Fig.". Please review this for the whole text.
- Table ?? contains all the data points used for answering RQ4 -> please add the correct reference for the table
- The authors use capital and lowercase for titles, journal titles and concepts in the list of references. I also noticed one of them including "cited by.." which might not be necessary. Please, review the list of references.
- "where the information was assessed given the full eligibility criteria present in Table 2" ". -> remove the space
- In Section 4, where the authors reference Table 3, they could state that this table is in the appendix to guide the potential readers.
- The data provided as additional output of this work should be provided with a permanent doi which can be obtained using platforms such as Zenodo or Figshare. It does not include a README file describing the content.
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