The Catalog allows you to see the list of the Maestro Stack, CloudFormation and Terraform templates already existing in the project and to manipulate these stacks. You can see the template details (source code), remove a template, or use a template as a basis for creating another one. Please note that the template list allows to see only templates available for the selected project. Press the Delete button to remove the selected stack (you can delete only stacks created by you). Press Duplicate to create a new template having the same source code. You can change it if needed, and save to the same or another project.
For more details on the Stack Template structure and general rules, please see our Maestro Stacks Guide, Section "2. Maestro Stack Template Structure". For more information about AWS CloudFormation, see AWS Utilization Guide, section 6.1. AWS CloudFormation Template Introduction. For more details about Terraform, please see the Services Guide, Terraform as a Service section.