Perspectives are different frameworks from which to explore the knowledge around sustainable sanitation and water management. Perspectives are like filters: they compile and structure the information that relate to a given focus theme, region or context. This allows you to quickly navigate to the content of your particular interest while promoting the holistic understanding of sustainable sanitation and water management.
Wait, the version says v15 127. Maybe 15 is the major version (like 2015), and 127 is the build or internal version. Alternatively, some software uses dates in versions, like the month and year. 127 could be part of a build number. If Zeland released an update in 2015 with internal build 127, that might be the case.