# Timing and Updates

## How often are the reports updated? {#how-often-are-the-reports-updated}

Commodity Production Costs analyses are updated on a quarterly cycle. Each quarter, the catalog is reissued as a new **Series**, with every analysis recalculated using that quarter's raw-material and utility prices, wage rates, and cost inputs.

Only the latest version of a report can be purchased. Once a new Series supersedes an earlier one, the earlier versions are retired and can no longer be bought — so any report obtained always reflects the most recent quarterly analysis for its process and country.

## What is the period of analysis? {#what-is-the-period-of-analysis}

!!! Summary
The period of analysis is the single quarter a report represents. Its raw-material and utility prices, wage rates, and resulting product value are all calculated for that one quarter — a point-in-time picture built from final data, with no forecasts.
!!!

The period of analysis is the single calendar quarter a report represents. Every price, rate, and result in the report belongs to that one quarter: the raw-material and utility prices, the wage rates, and the [product value](../glossary/p-r.md#product-value) that follows from them are all calculated for the period of analysis.

This makes each report a point-in-time picture. A report presents the production economics of its quarter — the product value calculated for the quarter purchased — rather than a running record of how those figures have changed over time. The analysis uses final data only; it contains no forecasts, so every figure describes the quarter analyzed rather than projecting a future one.

## What is the IC Index shown beside the period? {#what-is-the-ic-index-shown-beside-the-period}

The IC Index printed beside the period of analysis is the [Intratec plant construction cost index](../glossary/p-r.md#plant-construction-cost-index-ic-index) — a construction-cost index that anchors the report's capital-cost basis to its period of analysis. It expresses the relative cost of building a plant at a given time, and is used to scale capital costs from one period to another.

Showing it alongside the period places the report's capital investment on a common time basis, so capital-cost estimates stay comparable across quarters even as construction costs rise or fall.

## How are revisions within a quarter handled? {#how-are-revisions-within-a-quarter-handled}

!!! Summary
Each report in a quarterly Series carries a revision number, starting at Rev. 0 for the original release. Its Revision Control section logs every change — across the report's revisions and relative to previous Series — classified as a Fix, an Update, or an Improvement.
!!!

Within a quarterly Series, each report carries a revision number, beginning at **Rev. 0** for the original release. If a report is revised while still within the same Series, the revision number increments and the change is recorded in the report's **Revision Control** section.

Revision Control documents the changes made across a report's revisions and relative to previous Series, each classified by type:

- **Fix** — a correction of errors in a released report, such as typos or wrong descriptions and figures.
- **Update** — a change introduced with the release of a new Series, such as a technical parameter revised after a more recent publication.
- **Improvement** — a structural change applied across all reports, improving the accuracy of the estimates or the clarity of their presentation.

The result is a documented trail of what changed between one version of a report and the next.