| SIGMA_BLOCK_EXISTS | Block '$block' already exists | Tried to add a block with a name that is already present in the template | Choose a different name for a new block |
| SIGMA_PLACEHOLDER_NOT_FOUND | Variable placeholder '$placeholder' not found | There is no placeholder to replace by a new block in the template | Check the spelling of the placeholder name |
| SIGMA_PLACEHOLDER_DUPLICATE | Placeholder '$placeholder' should be unique, found in multiple blocks | A placeholder to be replaced by a new block should appear only in one place | Check the spelling of the placeholder name, choose a different placeholder |
| SIGMA_BLOCK_DUPLICATE | The name of a block must be unique within a template. Block 'blockname' found twice. | The added block contains a subblock that has the same name as the existing one | Check the $template and rename the block to something else |
