Any new SGML system to be developed and installed within a company will have been planned to some extent. An ROI analysis is used to determine how much the system will cost, how soon the system will pay for itself, and how much might be gained by the company over its planned lifespan. Usually, an ROI is done during the feasibility stage of a project. The ROI is published and passed before the Board of Directors, Tender Board, or other decision makers. If accepted, the project goes forward and the ROI justification goes on a shelf in the accountant's office.
Time goes by.
The system is procured, built, installed. Many factors in the initial feasibility study are adapted over time for changing conditions. At various phase milestones, the accountant takes the ROI off the shelf and looks to the actual experience of the system procurement, creation, or installation. Often, the scenario anticipated in the ROI is unrecognisable in real life. If the system is returning a reasonable gain to the organisation, it is difficult to detect.