ENCs are available as Base Cells or Update Patches. |
| Each ENC has an Update Application Date and Issue Date. |
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Base Cells are made available when each New Edition of an ENC is produced. |
- | The Update Application Date is the date that a Base Cell becomes available. |
- | In general, a Base Cell is produced when significant changes have been made to the ENC's coverage area, e.g., application of a hydrographic survey, channel alignment or shoreline modification. |
- | A Base Cell contains all the cartographic data within the coverage area of the ENC. |
- | The filename extension for a Base Cell is 000. |
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Update Patches can be made available many times during the edition life of an ENC. |
- | The Issue Date is the date that an Update Patch becomes available. |
- | In general, an Update Patch is produced when a critical change has been made to the ENC, e.g., application of a Notice to Mariner chart correction. |
- | An Update Patch only contains the cartographic data associated with the critical change, and must be applied to the Base Cell. |
- | The filename extension for an Update Patch is the number of the update, e.g., 001, 002, etc. These numbers are sequential and without omission. |
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