Guides to programming with AJAX, which is the core low level library used by all EMBOSS applications. The guides complement the on-line library documentation and are organised by topic and may cover more than one library file. They include the handling of ACD files, arrays, alignments, codon usage tables, exception messages, features, file input and output, graphics, lists, maths, matrices, menus, sequence patterns, phylogenetic data, application reports, sequences, translation, "simple" ACD datatypes, strings, system code and tables.