understanding the j i t rev 000

Understanding the Understanding the J.I.T. J.I.T. systemsystem

Just In TimeIntegrated into

Synchronized Production Lines

WorkshopsUsing the dice game simulationUsing the dice game simulation

The theory of ‘Just in Time’ or ‘J. I. T.’

• We often hear the expression ‘Just In time’ used by the Manufacturing Industries as well as by other commercial organizations. Unknown to many, this terminology is indeed quite meaningfull.

• Created a few decades ago by the Japaneese Automobile Industry, this new way of solving manufacturing issues can appear somewhat revolutionary to many when compared to the way we do things in North America.

• Why is it so important?• Simulating a typical production line behaviour by playing the

well known Dice Game, this PowerPointShow will demonstrate the advantages of the ‘Just In Time’ philosophy.

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The Dice Game

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The Law of probability• The Law of Probability states the following : If

a die is thrown a certain number of times and a count is kept of the number of dots that will appear on its face, it will invariably yield an average of 3.5.

• Or, if we add the numbers : 1+2+3+4+5+6 we will obtain 21. This number when divided by 6 (number of faces on the die) will yield 3.5

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Why go J. I. T.

• Now that we have established the random yield average of a die throw, let’s examine its relationship with the J.I.T. system.

• The J.I.T. is principaly a Manufacturing Production Line system for any type of equipment. Its main goal is to achieve ON TIME deliveries of the goods while controlling the inventories of either the finished pieces of the product as well as its components.

• If the various stages of the manufacturing process of a piece of equipment are not in ‘balance’ or do not have the same rythm or throughput, it will ensue a lack of a steady and continuous flow that will bring about bottlenecks somewhere in the production line. Also, this unbalance will cause large amounts of inventories dispersed everywhere on the shop floor. Needless to say that ON TIME deliveries will not be achieved.

• All the parts on the shop floor are therefore considered as incomplete goods and will end up on the Inventory list.

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Inventory = $$$• All uncontrolled inventories become a direct loss of money

for any industry and with time, may cause a possible shutdown of that plant. These large inventories are totally responsible for the direction of the 3 financial measurements as described in the following slide.

What is the goal of all companies ?

To make MONEY !

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Financial Measures

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Financial Measures• However, in order to determine the performance of a

Production Line, other measures are more appropriate for they better reflect what is being accomplished by the manufacturing unit.

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Financial Measures• Throughput T

– The Money gained by sales and not only by the production of parts as such.

• Inventory I– The Money invested into the purchase of RAW material.

• Operating Expenses OE– The Money invested into the transformation of RAW

material (Inventory I) into (Throughput T). Only the money for the wages.

KEYWORD = MONEY9

Financial Measures Let us examine our new manufacturing measurements

when compared to the financial measures.T (Throughput) directly affects NP (Net Profit), the ROI (return on investments)

and the CF (cash-flow). The same interaction exists for OE (operational expenditure or operating expenses).

Take notice of the direction of the RED ARROWS !THAT IS THE ULTIMATE GOAL !

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Simulation : The Dice game• Earlier on, we used a simplistic example with the throw of the die.• By fixing the flow of the line of production at 3.5 units, we were more

than generous since each die has 3 faces higher than 3.5, that is to say: faces 4, 5, and 6.

• Rare are the companies that require only the average yield from their production line; they aim rather towards the height of the capacities of each Station which forms this line of production for a product.

• Do they consider that several fortuitous factors can and will intervene without warning at a Stations or another? Seldom!

• But, when these unforeseeable occurrences appear, the complete line is disturbed and the fixed daily output is not met! In fact the inventories accumulate a little everywhere just as bottlenecks begin to form at the various Stations of the line.

• What can be done then? Let us examine first the course of the Dice game.

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Simulation : The Dice game

Station 1

Each evening, the supplier of raw material delivers 6 parts to Station 1 of the production line.

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Simulation : The Dice game

1 2 3 4 5 6

• During the nightshift, the setup man of the line ensures that every Stations is ready and he will produces a sufficient inventory at each Stations so that the following morning the operators can launch the production with a sufficient inventory of parts.

• It is absolutely necessary to underline the importance of the dependence of one Stations to the next knowing that each one brings a specific transformation to the product.

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Day One - Morning

As shown above : the Stations are ready for the start of a production cycleeach with adequate inventory.

The dice below, were thrown and symbolize the output for one day at Stations 1,2,3,4,5 and 6.

At Station 1, only one part is produced and must be passed to the second Station. The established throughput is 3.5 parts, therefore Station 1 did not meet its quota.

1 2 3 4 5 614

Day One - Evening

The inventory in reserve with each Station of the line of production at the end of one typical day of work in an unspecified factory has changed.

The dice below, had been launched and represents the output for the first day at Stations 1,2,3,4,5 and 6.

1 2 3 4 5 615

Day One – Analysis Stations 1 2 3 4 5 6

Inventory at start

6 6 6 6 6 6

Die thrown orProduction

1 5 6 3 4 2

6 – 1 = 6 + 1 - 5 = 6 + 5 - 6 = 6 + 6 - 3 = 6 + 3 - 4 = 6 + 4 - 2 =

Inventory at end of day

5 2 5 9 5 8

Raw materialdelivered to Station 1

+ 6 =11

Parts t sent to customer

2

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Day One - Observation• Note that the figures in red on the previous slide are parts transformed by

the preceding Stations.• Once transformed, they can pass to the following Stations and the same

applies to all the Stations. This is why the figures are of color blue when they are passed to the following Stations for another transformation.

• However, in reality the parts produced at Station 1 and passed to Station 2 in the same day cannot be added to the parts produced by Station 2 for this same day ; that Station has just received these unit and it must transform them in its turn!

• For a better comprehension of the system, this aspect of a typical line of production will not be taken into account. Let us assume quite simply that the transformation of the parts is instantaneous in order to better assimilate the concept!

• The following slideshows this alternative which will have to be taken into account in real life cases.

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Day One - ObservationStations 1 2 3 4 5 6

Inventory at start

6 6 6 6 6 6

Die thrownorProduction

1 5 6 3 4 2

6 – 1 = 6 - 5 = 6 - 6 = 6 - 3 = 6 - 4 = 6 - 2 =


5 1 0 3 2 4

Raw materialdelivered to Stations 1

+ 6 =11

Parts sent to customer

2

Alternative scenario assuming that the parts produced by a Station cannot be used by the

following Stations in the same day, because they would not have undergone any transformation

by that Station.

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Day One - Summary

Station 6

In spite of a sufficient inventory of 8 parts, the

last Station 6 of the production line was not able to deliver more than 2 parts to the customer.

Its objective was only 3.5

What happened? Were the dice loaded? No, the throw of the dicewas random to show Statistical Fluctuations and Dependent Events

that occur every day in Manufacturing Plants. I.E. : Breaking down of machinery, defective tool, non-conforming parts, etc.

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Day One – Night shift

Station 1

As usual, the supplier of raw material delivers 6 raw materials to Station 1.

5 were still in inventory due to its poor production of only one part during the day.

Station 1 will begin the second day with a Inventory of 11 parts.

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Day Two - Morning

Notice the inventory at each Station of the line for the beginning of a second typical day of work in an unspecified factory.

6 raw materials are always added to Station 1 during the previous night.The dice below, were thrown again and represent the output for

this second day at the Stations of production 1,2,3,4,5 and 6.

1 2 3 4 5 621

Day Two - Evening

The inventory at each Station at the end of the second day of work in an unspecified factory has now changed.

The dice below, had been thrown and represent the output for the second day at Stations 1,2,3,4,5 and 6.

Note the alarming small inventory at Station 2.

1 2 3 4 5 622

Day Two - AnalysisStations 1 2 3 4 5 6

Inventory at start

11 2 5 9 5 8


3 4 5 6 1 2

11 – 3 = 2 + 3 - 4 = 5 + 4 - 5 = 9 + 5 - 6 = 5 + 6 - 1 = 8 + 1 - 2 =


8 1 4 8 10 7


+ 6 =14

Parts sent to customer

2

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Day Two - Summary

Station 6

In spite of a sufficient inventory of 7 units,

Station 6 could deliver but only 2 parts to the

customer


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Day Two – Night shift

Station 1

As usual, the supplier of raw material delivers 6 parts to Station 1.

8 parts still remain following a poor production of only 2 parts during the

second day.

Station 1 will begin the third day with an inventory of 14 parts.

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Day Three - Morning

Notice the inventory at each Station of the line for the beginning of a third typical day of work in an unspecified factory.

The dice below, were thrown again and represent the output for this third day at the Stations of production 1,2,3,4,5 and 6.

1 2 3 4 5 626

Day Three - Evening

The inventory at each Station at the end of the third day of work has changed dramatically.

6 raw materials are always added to Station 1 during the previous night.

This represents the dice throw of that third day.Critical Situation at Station 3

This Station with a capacity of transforming 6 parts does not have any in inventory!

1 2 3 4 5 627

Day Three - AnalysisStations 1 2 3 4 5 6

Inventory at start

14 1 0 8 10 7


5 2 6 3 4 3

14 – 5 = 1 + 5 - 2 = 0 + 2 - 0 =NO PARTS

8 + 0 - 3 = 10 +3 - 4 = 7 + 4 - 3 =


9 4 0 5 9 8


+ 6 =15

Parts sentto customer

3

Bottleneck

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Day Three - Summary

Station 3

Critical situation at Station 3.

‘0’ inventoryand must produce 6 parts

for Station 4.

The production line is STOPPED !



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Day Three - Summary

Station 6

In spite of a sufficient inventory of 8 parts,

Station 6 could deliver only 3 parts.


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Day Three - Considerations• Station 6 of the production line did not succeed in delivering the 3,5

promised units to its customer although it was possible for it to deliver 6 units in a 8 hour day.

• More closely, let us look at the possible reasons which prevented Station 6 from delivering the goods.

• The transformation of a part at this Station was translated only into one simple operation of final inspection and packaging of the product. The time estimated for a part was only 1,5 hours.

• 3,5 parts can not be delivered, impossible to manufacture half a part. With the available time versus the time of transformation, it would have been easily possible to deliver: 4 parts X 1,5 hours = 6 hours. And 8 hours were at its disposal. In spite of that, Station 6 failed in the task. Why?

• Oh… the throw of the die is the culprit?• Then, let us examine closely this phenomenon… chance vs bad luck?

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Day Three - Considerations• Since the beginning of the production of these parts, all times

of transformation as well as set-up times at each of the 6 Stations had been evaluated and established by time measurements experts recognized in the field of manufacturing.

• With each Station, it was possible to produce easily a maximum of 6 parts in a 8 hour shift and allowing some spare time for any shortcomings.

• Q- WHAT IS THE SIGNIFICANCE OF THE THROW OF THE DIE?

• A- To understand and accept that there will always exist: DEPENDENT EVENTS and STATISTICAL FLUCTUATIONS

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Day Three - Considerations• The river analogy.

With time, the water or the inventory will overflow beyond the banks of the river and the COMFORT ZONE will disappear leaving only the obstacles that we have created ourselves indirectly by our lack of

planning and prevention and, by being unaware of the capacity of the resources at our disposal.

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The more rocks in the river, the more water is neededto navigate safely in the river.

Day Three - Considerations• There are 2 types of resources in a

manufacturing environment.

X

Y

A Bottleneck is a resource whose capacity is less than or equal to the market demand.

A Non-bottleneck is a resource whose capacity isgreater than the market demand.

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Day Three - Considerations• A surprise? Or a lack of prevention?• Could we have prevented it?

• Indeed… we could have… there was just the one part at Station 2 to begin the day’s production on the third day. In fact, less than the usual daily demand of 3,5 parts.

• What should have we done?• What could have we done?

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Operational Methods

X Y

Resource X has a capacityof only 80 pieces/day.

80 pieces will be passed on to

Resource Y has a capacityTo produce100 pieces/day.

Only 80 pieces will

be delivered to the

customer

Simulation 1

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Operational Methods

XY

Resource X has a capacityof only 80 pieces/day.20 incomplete pieces

will end up as Inventory.YYYYYYYYYYYYYYYYYYYY

100 pieces will be passed on to

Resource Y has a capacityto produce100 pieces/day.

Only 80 pieces will

be delivered to the

customer

Simulation 2Interdependence

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Operational Methods

X

Y

Y2Only 80

pieces will be delivered

to the customer

Delivers 80 pieces

Delivers 100 pieces

Assembly Station

Simulation 3Interdependence

Resource X has a capacityof only 80 pieces/day.

Resource Y has a capacityTo produce100 pieces/day.

Resource Y2 has a capacity to produce100 pieces/day can only assemble 80

and sent them to its customer. 20 incomplete pieces will end up

as Inventory.YYYYYYYYYYYYYYYYYYYY

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Operational Methods

X Y

Get rid of paradigms !

Activation

Utilization

= The employment of a resource to process materials.KEEPING THAT RESOURCE BUSY !

= The employment of a resource to process materialsso as to meet a timely scheduled demand .Contributes positively to the performance of the company.THROUGHPUT !

Operational MethodsManufacturing strategies must recognize :

• A : The level of utilization of a NON-BOTTLENECK resource is not determined by its own potential, but by the other constraints in the system.

• B: Resources should be UTILIZED and not ACTIVATED.

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Operational MethodsThe challenge is to change:

Efficiency machine ==== Strategic weapon

Change Shop Floor Measures from :

EfficiencyMeasures

Schedule Adherence

QualityStandards

PerformanceTo Standards

Schedule Adherence

QualityStandards

De :

À :

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Operational MethodsAn hour lost at a Bottleneck

is an hour lost for the total system andNOT RECUPERABLE !NOT RECUPERABLE !

An hour saved at a Non-Bottleneck is an hour of

OPPORTUNITY !OPPORTUNITY !

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The type of your production unit

V type

A type T type

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RAWMTL

RAWMTLRAW MTL

Analyse the various scenarios• V type plant

The raw material is transformed into various forms ofby-products and directed to dedicated stations.

Transformationstations

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RAWMTL

Analyse the various scenarios• Negative characteristics of a V type production line.

1- Will create piles of Inventory and WIP (work in process) all over the shop floor.

2- Unreliable deliveries and poor service.

3- Manufacturing complains about constant demandchanges.

4- Marketing complains about lack of responsivenessfrom production.

5- Interdepartmental conflicts are common.

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RAWMTL

Analyse the various scenarios• A type plant

The raw material is transformed into various forms ofby-products and directed to dedicated stations.

TransformationStations and

some are sharedresources.

3 or more production lines.

Hardware, etc.

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RAW MTL

Analyse the various scenarios• Negative characteristics of an A type production line.

1- Assembly station complains of SHORTAGES.

2- BOTTLENECKS appear to wander.

3- Lack of material synchronization.

4- Costs out of control (excessive overtime)

5- Integrated control is seen as KEY.

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RAW MTL

Data gathering• A : Define the environment in which the Business

operates.– Marketing Issues

• Open• Mature• Declining

– Competitive Element Sensitivity • Price• Product• Quality• Delivery

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Data gathering• B : Define the Flow: Product Flow Diagram.

– Floor layout• Equipement• Tool storage• Material handling issues

– Bills of Materials/Routings: High runners.– Demand Profile: Historic, Current and Forecast– Outside Services/Shared Resources– Stocking Points/Release Points for material.

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Data gathering• C : Assess General Conditions/Attitudes.

– Housekeeping• Tooling storage• Waste, etc.

– Attitudes• Cooperative• Hostile• Indifférent

– Communication• Internal• External

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Data gathering• D : Assess Constraints relative to Accomplishments.

– Demand– X et Y Stations– Types of…

• Physical resources– Machinery– Manpower– Tools/gauges– Space– Material

• Policy and Practices– Batching– Setup– Overtime– Priority definition and chain of decisions– Work rules, etc.

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Data gathering• E : Techniques for Identifying Constraints/Vulnerability.

A. Indicative WIP ( Work in process) B. Traditional problem partsC. Resource availibility

• Up time data• Identification of shared resources• Process reliability/repeatability• Scrap and rework

D. Load Profile/Capacity Analysis: Ensure basis of calculationE. Tooling and gauges

• Availability• Maintenance• Specific expertise required

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Data gathering• F : Techniques for Identifying Constraints/Vulnerability.

F. Quality issues and Outside Services: Turn around timeG. Required Support Services

• Engineering• Quality Control

H. Component Deliveries Issues• Raw Material and External Vendors

– How often– How much– Representative Expedite Lists

• Internal/Detail Deliveries– How often– How much– Historical data

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Data gatheringType V plant

In type V Plants, all products pass through similar resources. Analysis of due dateperformance will give us no hints.

The Key = Inventory Profile

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RAWMTL


• The Inventory will have a tendency to disperse at all available floor space.• Large Finished Goods Inventory with some very old items indicates sensitivity to set-ups.• Inventory will tend to build up before the constraint.• A dip in Inventory is the indicator of the location of the constraint.

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RAWMTL


The validity of the constraint location must be confirmed.

• Verification of the Overtime worked• Observation of the setups and process times.

These verifications will indicate the location of the constraint as the plant is run today.

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RAWMTL


We must identify where we want the ‘Constraint as a Drum’ to be located.

It may be different from where it is today.

This is one of the most important strategic decisions in a V plant.

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RAWMTL

Analyse the various scenariosType A plant

Inventory profile does not provide any clue.

There is Inventory everywhere !!!

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RAW MTL


Each department/station is not fed by a single other station but by many.

… Must look for other effects… !!!

… IMPACT will be on THROUGHPUT !!!

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RAW MTL


Bottlenecks X have problems producing parts.

At assembly, these parts will be missing !!!

Non-Bottlenecks Y will not have problems producing parts.

They will be available at assembly.

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RAW MTL


Start at the stores where the parts are :

1.Make a list of the parts that are short and those that you have in excess.

2.From this list define where the short parts are located .

THIS LIST WILL REVEAL WHERE THE SUSPECTED STATIONS ARE LOCATED !!!

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RAW MTL


Check the actual situation on the floor shop :

1.Check the Inventory at the Station you suspect to be the Bottleneck.

2.Have we used a lot of Overtime ot External resources to achieve our quota?

3.Are the ‘expeditors’ visits reguralerely those stations?

4.Do not put all your thrust in computor generator reports…

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RAW MTL

Analyser les scénariosType A plant

It could be quite possible that no Bottlenecks exist at any station on this line of production.

The problem may be one created by our ownscheduling system???

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RAW MTL

Managing Throughput

The 3 Ms

Measures (evaluate if our methods are acceptable)

Methods (the easiest facet to change) Mentality (the most difficult to change)

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Managing Throughput

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Mindset

Methods

Measures

Policies and Proceduresfor managing everyday’s production.

This is what we use todetermine if our methodsare good..Are we going in theright direction?

Culture… the way we think. Are we caught up

in Paradigms?

Managing Throughput• Identify the causes.

– The Market situation– Our Methods and Procedures– Our PerformanceSo as we can develop a review of our ways of thinking

based on : Simplicity Stability Focus

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Managing Throughput• So… the enigma is how can we maintain a (THROUGHPUT) T

of 70 units/month or 3.5 units/day ?

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Managing Throughput• The DRUM, the BUFFER and the ROPE

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Managing Throughput• The DRUM, the BUFFER and the ROPE

See the continuation on a PPS titled :Managing Material Flow

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Copyright 2008

understanding the j i t rev 000

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