From the Summary: "The Antideficiency Act (31 U.S.C. 1341-1342, 1511-1519) generally bars the obligation of funds in the absence of appropriations. Exceptions are made under the act, including for activities involving 'the safety of human life or the protection of property.' The interval during the fiscal year when appropriations for a particular project or activity are not enacted into law, either in the form of a regular appropriations act or a continuing resolution (CR), is referred to as a 'funding gap' or 'funding lapse'. Although funding gaps may occur at the start of the fiscal year, they may also occur any time a CR expires and another CR (or the regular appropriations bill) is not enacted immediately thereafter. Multiple funding gaps may occur within a fiscal year."
CRS Report for Congress, RS20348
Congressional Research Service: https://crsreports.congress.gov/