> ## 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.

# Concepts

> Nextedy POWERSHEET is built on a set of interconnected design principles that separate data structure from presentation and enforce process rules through configuration.

export const LastReviewed = ({date}) => {
  if (!date) return null;
  const formatted = new Date(`${date}T00:00:00Z`).toLocaleDateString("en-US", {
    year: "numeric",
    month: "long",
    day: "numeric",
    timeZone: "UTC"
  });
  return <p className="mt-10 text-sm text-gray-400 dark:text-zinc-500 not-prose">
      Last reviewed on {formatted}
    </p>;
};

## Architecture and Design

**[Powersheet Architecture](/powersheet/concepts/architecture)** -- How the server extension, client application, and YAML configuration layers fit together inside Siemens Polarion ALM.

**[Core Components](/powersheet/concepts/core-components)** -- The four building blocks of every powersheet: data model, sheet configuration, Powersheet Drive, and the document entry point.

**[Model-Driven Design](/powersheet/concepts/model-driven-design)** -- Why Powersheet uses a declarative data model to abstract Polarion work item types and link roles into a portable configuration layer.

## Configuration

**[Data Model vs Sheet Configuration](/powersheet/concepts/data-model-vs-sheet-config)** -- Understanding the separation between what data exists (data model) and how it is displayed (sheet configuration).

**[Configuration Hierarchy](/powersheet/concepts/global-vs-project-specific)** -- How YAML configuration files are discovered and loaded, scoping rules for global vs project-specific storage, and key YAML patterns used in sheet configurations.

## Data Modeling

**[Entity Types and Relationships](/powersheet/concepts/entity-types-and-relationships)** -- Defining `domainModelTypes`, mapping them to Polarion work item types, and declaring relationships with `from`, `to`, `cardinality`, and `linkRole`.

**[Navigation Properties](/powersheet/concepts/navigation-properties)** -- How `direct` and `back` create traversable paths used in expansion paths and column binding paths.

**[Link Cardinality](/powersheet/concepts/link-cardinality)** -- The meaning of `one-to-one`, `many-to-one`, `one-to-many`, and `many-to-many` cardinality values and how they affect the sheet UI.

**[Hierarchy and Traceability](/powersheet/concepts/hierarchy-and-traceability)** -- How expansion paths let you navigate multi-level entity hierarchies such as, for example, `UserNeed` to `SystemRequirement` to `DesignRequirement` in an RTM model.

## Constraints and Rules

**[Process Constraints](/powersheet/concepts/process-constraints)** -- Enforcing engineering methodology through `load`, `create`, and `pick` constraints that go beyond what Polarion provides natively.

**[Document Rules](/powersheet/concepts/document-rules)** -- Restricting where work items can be created or selected using `moduleFolder`, `moduleName`, `type`, and `component` constraints.

## Platform Integration

**[Polarion Integration](/powersheet/concepts/polarion-integration)** -- How Powersheet embeds inside Polarion as a server extension, registers administration pages, and stores configuration in SVN.

<Tip title="Where to start">
  If you are new to Powersheet, begin with [Powersheet Architecture](/powersheet/concepts/architecture) and [Core Components](/powersheet/concepts/core-components) to build a mental model of the system. Then move to [Entity Types and Relationships](/powersheet/concepts/entity-types-and-relationships) to understand the data model that drives everything else.
</Tip>

## See Also

* [Getting Started](/powersheet/getting-started/index) -- Hands-on tutorials for your first data model and sheet configuration
* [Reference](/powersheet/reference/index) -- Complete YAML property reference for data models and sheet configurations
* [FAQ](/powersheet/faq/index) -- Answers to common configuration and setup questions

<LastReviewed date="2026-07-02" />