The article discusses the interrelationships of the loxodrome or rhumb line, isometric latitude, and the Mercator projection of the rotational ellipsoid. It is shown that by applying the isometric latitude, a very simple equation of the rhumb line on the ellipsoid is obtained. The consequence of this is that the isometric latitude can be defined using the generalized geodetic longitude and not only using the geodetic latitude, as was usual until now. Since the image of the rhumb line in the plane of the Mercator projection is a straight line, the isometric latitude can also be defined using this projection. Finally, a new definition of the normal aspect of the Mercator projection of the ellipsoid is given. It is a normal aspect cylindrical projection in which the images of the rhumb line on the ellipsoid are straight lines in the plane of projection that, together with the images of the meridians in the projection, form equal angles as the rhumb line forms with the meridians on the ellipsoid. The article provides essential knowledge to all those who are interested in the use of maps in navigation. It will be useful for teachers and students studying cartography and GIS, maritime, or applied mathematics. The author uses mathematical methods, especially differential geometry. The assumption is that the readers are no strangers to mathematical cartography.

The increasing domains of digital technology in educational settings urgently require digital leadership (DL) to ensure the sustainability of school improvement initiatives in the digital era and to facilitate the digital transformation of educational institutions. DL emerges as an urgent and evolving topic of significant public interest. However, there is a notable lack of consensus persists regarding its definition and constructs within educational settings, hindering the advancement of DL theory. To address this gap, a systematic literature review was conceived, employing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. The primary aim was to enhance comprehension of the geographical and temporal distribution of relevant publications, as well as to elucidate prevalent definitions and constructs of digital leadership in educational contexts. This article endeavors to synthesize the extant scientific literature on DL, focusing on studies published between 2019 and 2024. Inclusion criteria encompassed scientific research publications sourced from Scopus and the Web of Science (WoS) databases, available in English, and centered on educational settings. Initial database queries yielded 578 papers, subsequently refined to 35 studies through meticulous screening for duplicity and adherence to inclusion criteria. Notably, the reviewed publications predominantly characterize DL as a multifaceted process, amalgamation, or integration, with a predominant emphasis on functional aspects of leadership. Noteworthy constructs frequently encountered include digital age learning culture, visionary leadership, excellence in professional practice, systemic improvement, and digital citizenship. This review contributes to the enrichment of theoretical conceptualizations surrounding DL. It underscores the imperative for future research to explore into the measurement of DL, thereby presenting promising avenues for evaluating principal DL within educational institutions.

As an essential principle in contract law, Indonesia has regulated good faith in the Indonesian Civil Code (the Dutch Civil Code that the Indonesian government uses based on the principle of concordance). However, the definition and benchmarks are not yet clear. There are no further provisions regarding the meaning and concept of this principle in the Indonesian Civil Code or other regulations. This absence of a single understanding of good faith principle in contract causes different opinions and legal certainty, whether from the business actor who signs the agreement or the judge as the third party who resolves contract disputes between parties. Therefore, future Indonesian contract law needs to regulate the definition and benchmarks for good faith principle. In order to find out the meaning and clear benchmarks for the good faith principle, the authors use a normative juridical method with a statute and conceptual approach. This research finds that the definition and benchmarks for the good faith principle is possible to be developed and regulated in Indonesian contract law. It shall set that good faith principle is based on honesty, decency, and fairness, which covers every agreement stage, from pre-agreement, agreement implementation, and after the agreement is completed.