What is "modca"

MO:DCA (Mixed Object:Document Content Architecture) is an IBM compound document format for text and graphics elements in a document. The 'Mixed Object' refers to the fact that an MO:DCA file can contain multiple types of objects, including text, images, vector graphics, and barcodes.

MO:DCA supports Revisable Documents, which are editable like revisable-form text, Presentation Documents, which provide specific output formatting similar to final-form text, and Resource Documents, which hold control information such as fonts. An MO:DCA file consists of a sequential, ordered hierarchy of independent objects - documents, pages, data objects, and resource objects such as fonts and ICC profiles. Each object is delimited by begin/end structures, and objects to be rendered specify presentation parameters and resource requirements in structures called "environment groups". Since the pages in MO:DCA documents appear in sequential order, presentation can start as soon as the first page is received.

Formats for specific objects are specified in various OCAs (Object Content Architectures): PTOCA for presentation text that has been formatted for output, GOCA for vector graphics objects, IOCA for bitmapped Images, FOCA for fonts, and BCOCA for barcodes. MO:DCA is implemented as IBM's Advanced Function Presentation (AFP) page description language.