SDF

• Simple Data Format, for binary data
• Spatial Data File, for geodatabases
• Standard Delay Format, for timing data
• SQL Server Compact Edition Database File (filename extension: .sdf)
• Structure data file, for chemical tables
• Scientific Data Format, a Hierarchical Data Format implementation

• Signed distance function (or field), in mathematical applications
• Syntax Definition Formalism, to describe formal languages

• Software development folder, a physical or virtual container for software project artifacts
• Synchronous Data Flow, a restriction of Kahn process networks
• SDF Public Access Unix System, a shared shell provider

• Südtirol Digital Fernsehen, a TV station in South Tyrol, Italy
• Super Dimensional Fortress, warships in the Robotech/Macross franchise
• Settlement Defense Front (SDF), an enemy faction of Call of Duty: Infinite Warfare

• Japan Self-Defense Forces
• State defense force, US
• Sudan Defence Force, 1925–1955
• Syrian Democratic Forces, North and East Syria

• Sikkim Democratic Front, India
• Social Democratic Federation (United States), 1936–1956
• Social Democratic Federation, UK, 1884–1911
• Social Democratic Forum, Hong Kong, 2000
• Social Democratic Front (disambiguation), Cameroon and Ghana
• Socialist Democratic Federation (Japan), 1978–1994

• Scouts de France, youth group
• Serb Democratic Forum, Serbs of Croatia
• Search Dog Foundation, rescue dog training organization

• Louisville International Airport, Kentucky, US (by IATA code)
• Soquel Demonstration State Forest, California, US

• Silver diammine fluoride, in dentistry
• Stromal cell-derived factor (disambiguation), SDF1, SDF1a, etc.
• Subwavelength-diameter optical fibre
• Synchronous diaphragmatic flutter or hiccup

• SDF Group (SAME Deutz-Fahr), an Italian-based agricultural machine manufacturer
• Simplified directional facility, an aviation instrument approach navigational aid
• Stochastic discount factor, in econometrics

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