The ease with which something can be maintained.(noun)
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Use "maintainability" in a sentence
"Automation scripts are just 'Code' at the end of the day and we can't deny the importance of having high quality of code and best practices adopted for making our automation tests not only readable and easy to troubleshoot but also for long term maintainability."
""The ease of system maintainability translates to high reliability for our customers.""
"Script# empowers you with a development methodology and approach that brings software engineering, long term maintainability and scalable development approaches for your Ajax applications, components and frameworks."