Writing & StyleStyle guide
Formatting File Name Extensions
Formatting File Name Extensions records the relevant Microsoft Style Guide convention while keeping it explicitly house-style scoped rather than presenting it as a universal grammar rule.
Write file name extensions in lowercase, such as .doc or .mdb, in Microsoft-style technical content.
Key details
Core IssueMicrosoft style says file name extensions use lowercase.
RegisterMicrosoft technical and professional documentation
Important caveats
Scope Boundary
Make literal product or code syntax exceptions only when the documented system requires different casing.
Further guidance
Content
Write file name extensions in lowercase, such as .doc or .mdb, in Microsoft-style technical content.
Purpose
Microsoft style says file name extensions use lowercase.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
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