It starts on page 23.
Plenty of analysis online by tax firms but I'll quote from this one: https://insightplus.bakermckenzie.com/bm/attachment_dw.actio...
> Generally, activities treated as software development for section 174 purposes include, but are not limited to, the following.
• planning the development of the computer software
• designing the computer software
• building a model of the computer software
• writing source code and converting it to machine-readable code
• testing the computer software (up to the point that a taxpayer places the computer software into service or determines that the computer software is ready for sale or licensing to others)
• producing product master(s), if the taxpayer develops the computer software for sale or licensing to others.
> Activities that are not treated as software development vis-à-vis software developed by a taxpayer for use in its trade or business are as follows:
• training employees and other stakeholders that will use the computer software
• maintenance activities after the taxpayer places the computer software into service
• data conversion activities, except for activities to develop computer software that facilitate access to existing data or data conversion
• installing the computer software and other activities relating to placing the computer software into service