# comodo-compliance v3.2.3

**Mercurial revision 5770:c90c3015e72d | 2026-05-22**

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## Description

`comodo-compliance` is a tool to **test the compliance** of NetCDF files with the **COMODO standards** (based on [CF Conventions](http://cfconventions.org/)).

It checks whether a given NetCDF file and its specified variables adhere to the expected grid and metadata structure. If the input file is a `.grd` file, the variable names are automatically prepended with `z`.

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## Usage

```bash
comodo-compliance [OPTIONS] file1 var11 [var12 ...] [file2 var21 [var22 ...] ...]
```

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## Options


| Option         | Description                                  |
| -------------- | -------------------------------------------- |
| `-h`, `--help` | Display this help message and exit.          |
| `-v`           | Enable **verbose mode** for detailed output. |


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## Examples

### **Basic Compliance Check**

Check compliance for a single file and variable:

```bash
comodo-compliance file.nc ssh
```

### **Check Multiple Variables in One File**

Check compliance for multiple variables in a single file:

```bash
comodo-compliance file.nc ssh tem sal
```

### **Check Multiple Files with Variables**

Check compliance for multiple files, each with its own variables:

```bash
comodo-compliance file1.nc ssh tem file2.nc sal
```

### **Check a `.grd` File**

For `.grd` files, the variable names are automatically prepended with `z`:

```bash
comodo-compliance grid.grd elevation
```

> **Note:** The tool internally processes this as `z_elevation`.

### **Verbose Mode**

Enable verbose mode for detailed compliance reports:

```bash
comodo-compliance -v file.nc ssh
```

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## Environment Variables

`comodo-compliance` does not use any specific environment variables. However, it relies on standard system libraries for NetCDF file handling.

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## Notes

1. **Input Files:**
  - Must be **NetCDF files** (`.nc` or `.grd`).
  - For `.grd` files, variable names are automatically prepended with `z`.
2. **Variable Specification:**
  - Variables must be specified **after** their respective file.
  - Example: `comodo-compliance file1.nc var1 file2.nc var2`.
3. **Error Handling:**
  - If no file is provided, the tool displays the help message and exits.
  - If a variable is specified without a preceding file, the tool aborts with an error.
4. **Correcting Files:**
  - Use **NCO (NetCDF Operators)** to correct non-compliant files. For example:
  - **Options for `ncatted`:**
    - `att`: Attribute name.
    - `var`: Variable name (use `global` for global attributes).
    - `mode`: One of `a` (append), `c` (create), `d` (delete), `m` (modify), or `o` (overwrite).
    - `type`: One of `f` (float), `d` (double), `l` (long), `s` (short), `c` (char), or `b` (byte).
    - `-O`: Overwrite the input file.

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## See Also

- [CF Conventions](http://cfconventions.org/)
- [COMODO Standards](https://www.comodo-ocean.fr/)
- [NCO (NetCDF Operators)](https://nco.sourceforge.net/)