ARINC Specification 844, prepared in two parts, defines the requirements of a Target Data Loader (TDL) from the target hardware point of view. Both parts are based on two data loading standards: Part 1 clarifies ARINC Report 615-3: Airborne Computer High Speed Data Loader, Part 2 clarifies ARINC Report 615-4: Airborne Computer High Speed Data Loader. ARINC Report 615 was originally written from the data loader point of view. It is important that a target designer have a general understanding of the operation of a data loader in its modern implementation. Equally important is the need for data loader manufacturers to understand the standardized implementation requirements and supported subset of ARINC 615 features that are defined in ARINC 844, Parts 1 and 2. Therefore, ARINC Specification 844 is expected to provide value to both data loader and target implementers. The referenced standardized implementation requirements and supported subset of features defined in ARINC 844, Parts 1 and 2 provide the blueprint for data loader implementations. This standard also requires the use of ARINC Report 665 Supplement 2 or later, or ARINC Specification 838 formatted loadable software parts. ARINC Report 615-3 represents the majority of data loaders used in air transport data loading operations. ARINC Report 615-4 added some features and changed others that were found in ARINC Report 615-3. Although these two supplements of the ARINC Report 615 are very similar, they are, in essence, two separate standards. Therefore, ARINC Project Paper 844 is written in two parts to allow the reader to easily reference between the two ARINC 615 standards. ARINC Specification 844, Parts 1 and 2, is applicable to a specific supplement to ARINC Report 615. This standard requires the use of ARINC Report 665-2 or later, or ARINC Specification 838 formatted loadable software parts. The guidance found in: ARINC Specification 844, Part 1, is applicable to: ARINC Report 615-3. The guidance found in: ARINC Specification 844, Part 2, is applicable to: ARINC Report 615-4.