ABSML is a new markup language that enables the creation of complex sentence formulas for 21st century automatic writing. ABSML tags replace parts of speech and sentence components using sophisticated semantic analysis, regular expressions, and web-based resources. In the right combination, the tags create prose that -- while based on formulas and code -- do not appear formulaic. ABSML is free and open for others to use, both through an online editor and an API (application programming interface).