In May 2001, Microsoft announced a program it called Shared Source, and for a few years the software world had a working alternative to open source that was not quite proprietary either. The premise was narrow: selected customers, governments, universities and partners could read Microsoft source code, in some cases modify it for their own use, under licenses that kept the code firmly Microsoft's property.

It was not open source, and it never claimed to be. But it is the most important counter-episode in the record, because it showed what the open shelf was competing against, and because it produced a family of licenses that still sit on the borderline today. Its posture is the one the enterprise shelf still keeps; an SAP and ABAP practice works inside the same grammar of visible code and narrow rights that Shared Source wrote down.

The program on the page

Shared Source was not one license but a portfolio. At the permissive end, the Shared Source license for certain tools let developers read, modify and redistribute. At the restrictive end, government and enterprise programs let a customer read the Windows source under strict conditions, inside a secured room, with no right to take anything away. Between them sat the licenses for Windows CE, for academic use, for reference only. The common trait was the same: the source could be seen, and the rights stayed with Microsoft.

The program was a defensive and an offering at once. It answered the growing demand for source transparency from governments and large customers, while keeping every right the company cared about.

What it was answering

The timing mattered. In 2001 the GPL was spreading through the industry, governments were asking whether public money should buy code they could not inspect, and the Halloween Documents had already shown Microsoft's internal anxiety about open source. Shared Source was the company's answer: you could look, under supervision, but the commons stayed closed. It was the open source idea translated into a form that preserved every existing revenue line.

The same guarded grammar survives in the enterprise world, where the code is everywhere and the rights are narrow. The difference is that the enterprise shelf never pretended to be a commons; Shared Source's significance is that it was the moment the boundary between the two was drawn in public.

Where it overlapped with collaborative source

The Jahia license and the Shared Source program were drafted almost at the same moment, and they were reaching for adjacent ideas: keep the source visible, keep the commercial rights controlled. The difference was intent. Collaborative source wanted the community to develop the code and to pay or contribute when they used it commercially. Shared source wanted the customer to see the code and to keep paying for everything else. One was an experiment in funding a commons; the other was a strategy for keeping a fortress transparent.

The licenses it left behind

The program's longer legacy is in the licenses that outlived it. The Microsoft Public License and the Microsoft Reciprocal License, both eventually approved by the Open Source Initiative, are genuine open source texts descended from the same drafting effort. The reference-only licenses, the look-but-do-not-touch texts, remain on the borderline shelf where the binder files everything that opens the code to reading without opening it to use.

That borderline shelf is more crowded than it looks. Source-available licenses, evaluation licenses, reference licenses and the shared source texts all live there, each one giving the reader something short of the four freedoms and calling it by a name that sounds close to open.

The era it closed

It also left the record with a vocabulary problem. Shared, open, and source-available have been used interchangeably in press releases ever since, and part of the binder's work is keeping the difference legible. The shared source texts are the reason the definition exists in writing: somebody had to draw the line a marketing department kept blurring.

Shared Source faded as a named program when Microsoft itself moved toward open source in the 2010s, eventually releasing code under real open licenses and joining the Open Source Initiative. The era it named is closed, but it left the record with a permanent question: how much access is enough? The shared source texts proved that reading the source was not the same as being free to use it, and the binder files them as the clearest demonstration that the word open has a spectrum the definitions are there to police.

The counterexample on the shelf

The record keeps the shared source sheet because it is the cleanest counterexample to open source ever mounted by a major company. It showed that source access alone was a negotiable quantity, that a license could give the community everything except the rights, and that the difference was worth an entire licensing program. The collaborative source experiment was trying to solve the same transparency problem from the opposite direction.

The program's real lesson is that the shape of a license follows the shape of the holder's interests. Microsoft wrote shared source because its interests were transparency without redistribution; the community wrote open source because its interests were the opposite. Reading the license means reading which interest it was drafted to protect.

What the text grants

Read access to source, and sometimes modification for internal use, with all substantive rights retained by the owner.

What a reader should check

Whether a license that opens the source also opens the rights to use, modify and redistribute it.

The limit of this reading

The program is a historical record; Microsoft's later open source work is a separate chapter of the story.