> For the complete documentation index, see [llms.txt](https://docs.intrepidcs.com/vspy-3-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.intrepidcs.com/vspy-3-documentation/3.9.14/vehicle-spy-main-menus/main-menu-embedded-tools/ecu-flashing-documentation/2.-cal-files-and-dids-parameters.md).

# 2. CAL Files and DIDs (Parameters)

#### **2.1 CAL Files**

\- CAL Files are sets of calibrations or adjustments stored in a single file, often in FLASH memory.

\- They are primarily used in Powertrain ECUs to fine-tune performance parameters.

#### 2.2 DIDs - Diagnostic Identifiers

\- DIDs are parameters or adjustments stored in FLASH or NVRAM, accessible via ISO 14229 (UDS).

\- DIDs are frequently used to configure an ECU with specific options, typically at End-of-Line (EOL) stages.

<figure><img src="https://lh6.googleusercontent.com/Pd0qcbAlRNdDc_R8Fv1KqiUf3dUR96ptJuspdDLafnK6A6PRQBG1KjBEp1yjDN_EgKaZmIPC-uPRF4cRK4OqVNAo3wa6_knOEB_WvZouBP2bCp3W8xzFxsYsQWnwPkdwr4XJeqy_VtV8QoP_eucGsdo" alt=""><figcaption></figcaption></figure>


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