K-line may refer to: Chemistry K-line (spectrometry), one of two features in spectroscopy: Calcium K line, a Fraunhofer spectral line from ionised calcium K-line (x-ray), an x-ray peak in astronomical spectrometry K line, a term used in Internal conversion electron spectroscopy Computing K-line (artificial intelligence) (Knowledge-line), a mental agent in artificial intelligence K-line (IRC), a server ban in IRC Finance Candlestick chart, or K-line, a style of financial chart used to describe price movements of a security, derivative, or currency Sports K line, the line marking the calculation point in ski jumping Transportation K (Broadway Brooklyn Local), earlier KK, discontinued in 1976 K (Eighth Avenue Local), a defunct train service on the New York City Subway, which was known as the AA until 1985 K Ingleside, a service of the San Francisco Municipal Railway sometimes called the K Line K Line (Los Angeles Metro), a light rail line in Los Angeles County, California K (Los Angeles Railway), defunct streetcar line in Los Angeles, California K Line, a Japanese shipping company K-Line, a model railway locomotive company K-Line bus operator in Yorkshire, England since rebranded as Tiger Blue K-Line, part of the ISO 9141 on-board diagnostics vehicle network interface standard