Repertory is the medium for conducting the exercise of Repertorisation,thus repertory act as a medium for Repertorisation.
We may use one Repertory or more than one for this exercise. Thus depending on the number of repertories used the medium of Repertorisation may be classified as

#. Unitary medium
#. Multiple medium
   * Comparative
   * Integrated 

UNITARY MEDIUM
In this only one Repertory is used for the whole case
The Repertory is selected on the basis of operating schools of philosophy
All the symptoms which are to be Repertorised are found in that Repertory
The unitary medium affords the easiest passages all the rubrics are found under one roof.

MULTIPLE MEDIUM / CROSS REPERTORISATION
Here more than one Repertory is used for the given case.
The term cross repertorisation is used when more than one Repertory is consulted either to help in the selection of the similimum or to confirm the result obtained from the use of one Repertory.
 PURPOSE
1. To highlights the oneness of all the Repetories with regards to their objective i.e. to find the similimum
2. To select well represented rubrics from any of the Repertories.

Further divided in to
Comparative medium
Integrated medium

COMPARATIVE MEDIUM
Here the same set of symptoms are repertorised in different repertories.
Quite often an academic exercise, to understand & appreciate the relative value of different repertories for the given case.
Useful when the operating schools of philosophy cannot be determined
The medicines which are leading in the repertorial result may not tally between different repertories.
More time consuming process

INTEGRATED MEDIUM
Indications :
When all the required rubrics are not found in a single repertory
When there is no clarity as regards to the operating schools of philosophy in the case.
When the operating schools of philosophy is vague or more than one schools of philosophy is indicated then the dominant schools of philosophy has to be determined. This is determined on the basis of the nature of the symptoms found in the case.
The repertory thus selected is called the Base repertory and the other repertories are called Accessory repertories.
The multiplicity of repertories may belongs to the same schools of philosophy or to different schools.
In a case when all the repertories belongs to the same schools of philosophy ,the repertory which affords the major share of rubric is called as the Primary repertory ,and the repertories which contribute for lesser number of rubrics are called Secondary repertories
If some symptom has to be accessed from a repertory not belongs to the same schools of philosophy as the primary repertory such repertory is called as Accessory repertory
Eg . Synthesis for Generals
      Kent for particulars
While using the integrated medium, it has to be remembered that the grading of medicines in different repertories is not the same. So we have to consider the scale of grading of the primary       or the Base repertory as the bench mark and convert the grades of medicines in the Secondary or accessory repertories.
Eg, If Kent's repertory is used as Base repertory & TPB & Boerick as accessory repertories, then 
* The 1st grade of TPB scores 3 instead of regular 5
* The 2nd grade " 2 " 4
* The 3rd & 4th " 1 " 3
                 And
* The 1st grade of Boerick 3 " 2
* The 2nd " 2 " 1

REFERENCES
Munir Ahmed : Introduction to Repertorisation
Tiwari : Essentials of Repertorisation
Patel.R.P The art of case taking & Practical repertorisation