This section explains how a model developer can use Invantive Control for Excel using the buttons on the ribbon in Microsoft Excel. The model developer can use the same functions as the model user, but the developer can also modify the model. The following image shows the ‘Modeller’ tab with the buttons available to the model developer. This section explains the function of each button.  The ‘Modeller’ tab is divided into the groups ‘Synchronise’, ‘Publish’, ‘Model Information’, ‘Block Actions’, ‘Connection’ and ‘Help’. This tab is only visible if development mode is enabled in the [Configuration](invantive-control-configuration). Model  The “Model” group contains the following buttons: - Design Mode: enables or disables the workbook’s design mode. The model can be modified in design mode. When enabled, you will be prompted for a password if one has been set. - Edit Model: edit the model of this workbook. The window displays the parameters, blocks, extensions and pending changes. See [Model Editor](invantive-control-model-editor). - Validate Model: validates the designed model. If validation fails, an error message will appear. - Install Database: install the model database in this worksheet. - Update Database: upgrades the database model in this workbook to the latest version supported by Invantive Control for Excel. The button only works if an update is available. - Remove Database: remove the database model from this worksheet. This action cannot be undone and synchronising changes will no longer be possible afterwards. Tools  The “Tools” group contains the following button: - Query Tool: opens the Query Tool to execute an SQL query on the database; see [Invantive Producer Query Tool](invantive-query-tool). Block Information  The “Block Information” group contains the following button: - Block Information: this displays information about the selected block, including the source code and whether the block can be edited. Row Information  The “Row Information” group contains the following button: - Row Information: this displays information about the selected row, including the unique ID, status and field from the fact database. Debugging and Analysis  The “Debugging and Analysis” group is only visible when debug mode is enabled and contains the following buttons: - Repository Worksheets: displays the hidden worksheets. The repository contains a workbook with the model database and an empty worksheet. See [Repository Worksheets](invantive-control-repository-worksheets). - Show Trace: opens a window with the debugging and analysis tools. This window can be used to analyse any errors in the operation of Invantive Control for Excel, see [Show Trace](invantive-control-show-trace). - Mark Row as New: mark this row as new so that it can be inserted into the fact database during the next synchronisation. This function can be used when copying data between two fact databases.