Home / File Formats

File Formats

ProTest works with two model file formats. The native format is .cahtt (JSON). ProTest can also import and export .pict files for interoperability with Microsoft's PICT tool.

Formats at a Glance

Format	Extension	Native?	Contains
.cahtt	.cahtt	Yes	Full model + settings + saved results
.pict	.pict	No (import/export)	Parameters, sub-models, constraints

Which Format to Use

• For ProTest work — Always use .cahtt. It stores everything in a single JSON file.
• For sharing with PICT users — Export to .pict. This format is compatible with Microsoft's standalone PICT command-line tool.
• For importing existing models — ProTest can import .pict files and convert them to .cahtt.

The .pict format is provided only for interoperability with existing PICT workflows. It is a limited text format that loses significant information compared to .cahtt.

What You Lose with .pict

Feature	.cahtt	.pict
Parameters and values	Yes	Yes
Value weights	Yes	Yes
Negative values (~)	Yes	Yes
Value aliases (\|)	Yes	Yes
Sub-models	Yes	Yes
Constraints	Yes	Yes
Seeds	Yes	No — PICT uses a separate seed file
Engine selection (PICT vs SIPO)	Yes	No
SIPO tuning (Base, T-Init, T-Final)	Yes	No
Interaction order	Yes	No — passed as a command-line flag in PICT
Randomization settings	Yes	No — passed as a command-line flag in PICT
Case-sensitivity setting	Yes	No — passed as a command-line flag in PICT
Saved generation results	Yes	No
Saved trial results	Yes	No
Saved verification results	Yes	No
File version tracking	Yes	No

In short, the .pict format only stores the model definition (parameters, sub-models, constraints). Everything else — seeds, generation settings, engine choice, and results — is lost on export.

Output Formats

When generating results, ProTest can output in several formats:

Format	Extension	Description
CSV	.csv	Comma-separated values
Markdown	.md	Markdown table (for documentation)
JSON	.cahtt	Full model + results
PICT	.pict	Model text only (no results)