> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/developers/paramml-developer-guide/what-are-object-and-parameter/parameters.md).

# Parameters

In ParamML, parameters are defined using

tags. They specify a value using a constant, expression, or reference to an object. Every parameter must or may have a name (N), value (V), type (T) and description (D). The name (N) attribute is used to identify the parameter, the value (V) attribute is used to specify the value of the parameter, the type (T) attribute is used to specify the type of the value, and the description (D) attribute is used to provide a brief explanation of the parameter.

For example,

specifies a parameter named "length" with a value of "10", a type of "Number" and a description of "The length of the structure".

**Example**

```xml
<P N="L" V="100" D="Lenght" />
```

```xml
<P N="Desc" V="This analysis is applicable" T="Text" />
```

```xml
<P N="Beam" V="ASTM A992" T="Steel Material" D="Beam Grade" Role="Input" Category="Material Properties"
```

**Attributes of Parameters**

| 1 | **Symbol** | **Label** | **Description**                                                                                                                                                                                                                                                                                   | **Mandatory** | **Example** |
| - | ---------- | --------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------- | ----------- |
| 2 | T          | Type      | In ParamML, the type (T) attribute specifies the type of the parameter. By default, all parameter values are expressions or numbers that can be evaluated mathematically. In this case, the type attribute is only specified or included in the parameter if it is a text or an object reference. | Yes           | T="Text"    |

T="Surface"

T="Volume"\
\| 3 | N | Name | The name (N) attribute specifies the name of the parameter. It should be short and meaningful, and should not contain any spaces or special characters.

Numbers can be used, but the first character of the name cannot be a number. The "\_" (underscore) is commonly used in the name of parameters to specify the subscript of a parameter. | Yes | N="height"

N="width"

N="NumberOfRebars"

N="Radius1"

N="L\_b"\
\| 4 | V | Value | The value (V) attribute specifies the value of the parameter. This could be a constant, expression, text, or an object reference. | Yes | V="10" | | 5 | D | Description | The description (D) attribute specifies the description of the parameter. Words placed before the ":" (colon) will appear in the interface as the heading of the description.

Anything enclosed in "\[ ]" (square brackets) and separated with a "/" (slash) will appear in a drop-down in the interface as options for the value of the parameter.

These options will show up in the edit dialog box of the object defined by the parameter. | No | D="Height of the column (ft)"

D="Material: The default material of the section."

D="Force Unit: The force unit of the unit system. \[POUND/KIPS/NEWTON/ KILONEWTON/MEGANEWTON/TON/M-TON/KGF]

| 6 | UT | Unit Type     | Specifies the **type of unit** used by the parameter                                                                                               | No | UT="Length" |
| - | -- | ------------- | -------------------------------------------------------------------------------------------------------------------------------------------------- | -- | ----------- |
| 7 | UC | Unit Category | Specifies the **name of the unit system** used by the parameter UC attribute must have the name of one of the unit objects defined in the project. | No | UC="Section |


---

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