The sequence folder contain all the ectd information.  When you submit an application for market authorization Regulatory agencies such as Health Canada apply certain validation rules to determine compliance with the eCTD guidelines. Your submission will not be accepted unless it complies with the guidelines. Submitting an eCTD dossier is team work. Several people will have been involved at various stages.  I will discuss the following 7 general rules as they apply to Health Canada.sequence folder

1. Do not include empty folders

An eCTD  folder must contain at lest a sub folder or a file. Folders without at least a sub folder or a file should not be submitted to Health Canada. All the folders are in the sequence folders which is characterized by 4 digits.


2.Remove all file and folder security

Your purpose for submitting a dossier to Health Canada is to get it reviewed. If for any reason the file or folder is protected the review will not take place. A validation software will check in the  sequence folder structure to determine if there are  files or folders in which there are settings that deny the user access .

3.Beware of file size when authoring documents

When you are authoring  documents you must be aware that you have limitations in terms of file size. You must organize your work . You will get a warning if your pdf files are  150-200 MB . These are fairly large files. If you have other files such as data files excluding SAS XPT you will get a warning during validation if the file is larger than 100 MB.

The maximum file size is 200 MB for pdf files and 1GB for SAS XPT . You will get an error if you exceed this limit. Plan your work early so that splitting a file will not turn out to be a burden.

4.Sequence folder requirements

Although people will use eCTD software to file ectd dossiers, failure to understand the rules can cause errors during submission especially in assigning sequence numbers. Remember that the first submission for generic product A must be 0000. The next submission will increase by 1 so that its 0001. Checks the sequence folder name. You will get an error message if Fif the sequence appears  to be initial sequence but its name is not the expected 0000. you will get an error if you mix up sequences such that you you create 0003 before 0002.

5.XML Backbone

The ICH files will be found in the util folder. Some regional files will be found in the m1 folder and util folder. The index file should be in the sequence folder as shown below. If you have wrong files or invalid files in the util folder the validation software will report an error.

my sequence folder story

6.Review information in Study tagging files

The purpoe of Study Tagging Files (STFs) is to organize clinical and non clinical data in a standardized way that helps  eCTD review. Its equivalent in some way to the index.xml in structure and purpose.

If you have invalid STF files  in the sequence folder they will be reported as errors. A common mistake is failure to QC the metadata . This can limit the value of your STF files.  It is proposed that you have a system in place to QC all the metadata in your STFs.

7.Sequence numbering

As mentioned earlier you should ensure that each successive transaction which you have provided in the life-cycle of the  application, has a sequence number that is sequentially  increased  by 1 number. An example would be 0001,0002,0003,0004,0005 and so on .

You may not skip numbers. To avoid this keep a record of  sequence Numbers that have been allocated for each dossier you submit. If you skip you will receive validation errors. For example if you skip sequence number 4. Validation report for sequence number 5 will report an error.


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If you are new to eCTD and would like training contact us . If you would like help in submitting a dossier to Health Canada or to FDA you may also contact us.