> ## Documentation Index
> Fetch the complete documentation index at: https://learn.nextedy.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Data Model Basics
> Data Model Basics — common questions about Nextedy POWERSHEET.
export const LastReviewed = ({date, state}) => {
if (!date) return null;
const formatted = new Date(`${date}T00:00:00Z`).toLocaleDateString("en-US", {
year: "numeric",
month: "long",
day: "numeric",
timeZone: "UTC"
});
const label = state === "reviewed" ? `Last reviewed and confirmed up to date on ${formatted}` : `Last updated on ${formatted}`;
return
{label}
;
};
The **data model** is a YAML configuration file that defines the semantic layer between Polarion's native work item types and Powersheet's sheet views. It maps Polarion types, link roles, and custom fields into structured entity types and relationships that Powersheet uses for querying, displaying, and editing data. Without a data model, Powersheet cannot understand which work items to load or how they relate to each other.
See the [Data Model Reference](/powersheet/reference/data-model/index) for the complete property reference.
Data models are managed through the Polarion administration interface at **Administration > Nextedy POWERSHEET > Data Models**. You can create both global models (available to all projects) and project-specific models. Multiple models can coexist, and each sheet configuration references a specific model by name.
The three configuration layers are connected through navigation property names:
* **Data model** defines entity types and relationships (with `direct` and `back` navigation names)
* **Sources** define how to query and expand those relationships (using the navigation names)
* **Columns** define how to display the resulting data (using dot-notation binding paths)
The cardinality of a relationship determines the expand pattern and column binding syntax. See the [Sheet Configuration Reference](/powersheet/reference/sheet-config/index) for column binding details.
