Medical Adhesive-Related Skin Injury (MARSI): Signs, Causes, and Prevention
Medical tapes, adhesive dressings, electrodes, securement products, and other adhesive medical devices are used every day to hold dressings and equipment in place. However, when an adhesive is unsuitable for the skin, applied under tension, exposed to excess moisture, worn under changing conditions, or removed incorrectly, it may damage the skin it was intended to protect.
This type of damage is known as medical adhesive-related skin injury, commonly abbreviated as MARSI.
MARSI is not simply another name for a medical tape allergy. It includes several types of skin damage, such as skin stripping, tension blisters, skin tears, irritant dermatitis, allergic contact dermatitis, maceration, and folliculitis.
Reducing the risk requires more than choosing a product labeled for sensitive skin. Skin assessment, the level of fixation required, moisture control, tension-free application, wear conditions, and careful removal all matter.
Important: This article provides general educational information. Persistent redness, broken skin, blistering, significant pain, recurrent reactions, or possible infection should be assessed by a qualified healthcare professional.
Quick Answer: What Is Medical Adhesive-Related Skin Injury?
Medical adhesive-related skin injury, or MARSI, is skin damage associated with the use or removal of a medical adhesive product or device. It may appear as persistent redness, superficial skin stripping, a skin tear, blistering, dermatitis, white softened skin, or inflamed hair follicles.
MARSI is not always an allergic reaction. It can result from excessive adhesion, fragile skin, adhesive tension, swelling, trapped moisture, repeated dressing changes, incompatible products, or removing tape too quickly or at a high angle.
A commonly used clinical definition includes redness or another skin abnormality that remains for at least about 30 minutes after an adhesive is removed. However, this time criterion alone should not be used to diagnose the problem. The appearance of the skin, symptoms, timing, adhesive location, and other possible causes must also be considered.
What Does MARSI Look Like?
MARSI can look different depending on how the skin was damaged. Possible signs include:
- Redness that remains after the adhesive is removed
- Shiny, raw, moist, or peeled skin
- Loss of the superficial skin layer
- A flap-like or irregular skin tear
- Blisters near or beneath the adhesive edge
- Burning, itching, tenderness, or stinging
- A rash that follows the shape of the tape or dressing border
- White, pale, soft, swollen, or wrinkled skin
- Small red or pustular bumps around hair follicles
- Bleeding or open skin after adhesive removal
Brief pressure marks or temporary redness do not automatically confirm MARSI. On the other hand, significant peeling, blistering, open skin, or persistent discomfort should not be dismissed as a normal tape mark.
Appearance alone may not identify the cause. Infection, pressure, friction, moisture-associated skin damage, eczema, and other skin conditions can resemble adhesive-related injury.
Types of Medical Adhesive-Related Skin Injury
MARSI is commonly grouped into mechanical injuries, dermatitis, and other skin complications associated with adhesive use.
| Type | Typical appearance | Common mechanism |
|---|---|---|
| Skin stripping | Shiny, red, raw, moist, or peeled area | Superficial skin cells are removed with the adhesive |
| Tension injury or blister | Blistering or separation near an adhesive edge | Tape or a dressing border is stretched, or the skin moves or swells underneath it |
| Skin tear | Skin flap, split, irregular opening, or partial tissue loss | Mechanical force damages fragile skin during adhesive removal |
| Irritant contact dermatitis | Red, burning, sore, dry, cracked, or sometimes weeping skin | Direct irritation or damage to the skin barrier |
| Allergic contact dermatitis | Itchy, inflamed, eczema-like rash that may extend beyond the contact area | Delayed immune reaction to an adhesive ingredient or related substance |
| Maceration | White, pale, soft, swollen, wet, or wrinkled skin | Sweat, wound drainage, or other moisture remains trapped against the skin |
| Folliculitis | Small red or pustular bumps centered around hair follicles | Occlusion, moisture, friction, hair, or follicular irritation |
More than one type can occur at the same time. For example, moisture may weaken the skin, making it more likely to strip when the adhesive is removed.
Skin Stripping From Medical Tape
Skin stripping is one of the most recognizable forms of mechanical MARSI.
It occurs when the bond between the adhesive and the outer skin is stronger than the connections holding superficial skin cells together. When the adhesive is removed, part of the skin surface remains attached to the tape or dressing.
The affected skin may appear:
- Shiny or glossy
- Red or pink
- Moist or raw
- Tender or stinging
- Clearly shaped like the removed tape or adhesive border
Skin stripping is a mechanical injury. It does not necessarily mean the person is allergic to the adhesive.
Risk may increase when the same area is repeatedly taped, when a high-strength adhesive is used for a light fixation need, when skin is fragile or moist, or when tape is pulled quickly and vertically away from the skin.
Tension Injuries and Adhesive Blisters
A tension injury can develop when the adhesive product and the skin move differently.
Common contributing situations include:
- Stretching tape before pressing it onto the skin
- Pulling an adhesive dressing border tightly during application
- Placing a rigid adhesive across a joint or curved area
- Applying the product while the body part is in an unnatural position
- Swelling that develops beneath a firmly fixed adhesive
- Repeated movement that creates shear at the adhesive edge
These forces can separate layers of skin and produce a blister, especially near the edge of the adhesive.
Application principle: Medical tape and adhesive dressing borders should generally be laid onto the skin without unnecessary stretch unless the individual product specifically instructs otherwise.
Skin Tears Caused by Adhesive Removal
A skin tear is a traumatic wound caused by mechanical force. Adhesive removal is one possible cause, particularly when the skin is thin, dry, fragile, or already damaged.
During removal, the skin may split or form a flap instead of separating cleanly from the adhesive. This is more common in older adults, infants, people with long-term illness, and anyone whose skin barrier has been weakened.
Current international recommendations for preventing and managing skin tears in aged skin recognize adhesive removal as one of the mechanical forces that may cause a skin tear.
However, not every MARSI is a skin tear. Superficial stripping, dermatitis, blistering, maceration, and folliculitis can also be adhesive-related injuries.
For more detail, review how adhesive removal can contribute to skin tears and how dressing choice changes for fragile skin.
Irritant vs. Allergic Contact Dermatitis
Red or itchy skin beneath medical tape is often described as an allergy, but dermatitis can be irritant or allergic.
| Feature | Irritant contact dermatitis | Allergic contact dermatitis |
|---|---|---|
| Cause | Direct irritation or disruption of the skin barrier | Immune reaction to a specific ingredient |
| Typical symptoms | Burning, soreness, redness, dryness, or weeping | Itching, redness, swelling, or eczema-like rash |
| Distribution | Often limited to the direct contact area | May match the contact area or extend beyond it |
| Timing | May appear relatively soon after irritation | Often delayed after exposure |
| Assessment | Based on exposure history and examination | May require professional assessment or patch testing |
This comparison cannot confirm which condition is present. Repeated reactions, spreading rashes, severe itching, blistering, or symptoms that continue after the product is removed should be professionally evaluated.
Maceration Under an Adhesive Dressing
Maceration occurs when the skin remains exposed to too much moisture for too long.
Moisture may come from:
- Wound drainage
- Heavy sweating
- Water entering beneath a lifted dressing edge
- Applying the adhesive before cleansed skin is dry
- An absorbent dressing that cannot manage the amount of exudate
- An occlusive dressing used in unsuitable conditions
Macerated skin may appear white, pale, gray, soft, wrinkled, or soggy. It may also become more vulnerable to friction and adhesive removal.
This means a person may initially develop moisture damage and then experience stripping when the dressing is changed.
Learn more about why excess moisture may make the skin around a wound white, soft, and easier to damage.
Folliculitis Beneath Medical Tape
Folliculitis appears as small red, inflamed, or sometimes pustular bumps centered around individual hair follicles.
Possible contributing factors include:
- Prolonged occlusion
- Heavy sweating
- Friction under the adhesive
- Hair being pulled or trapped
- Repeated application over the same area
Not every cluster of red bumps is an adhesive allergy. The location of the bumps around individual hairs may suggest follicular irritation, but professional assessment may be needed when the area is painful, spreading, draining, or persistent.
Is It MARSI, an Allergy, or Something Else?
Not every reaction beneath medical tape is an allergy. MARSI is a broad category that may involve mechanical damage, moisture, irritation, or a true allergic response.
| Finding | Possible explanation |
|---|---|
| Shiny or peeled skin immediately after removal | Mechanical skin stripping |
| Blister near a stretched dressing edge | Tension injury |
| Irregular split or skin flap after removal | Adhesive-related skin tear |
| Burning redness limited to the contact area | Possible irritant dermatitis |
| Itchy, eczema-like rash | Possible allergic contact dermatitis |
| White, soft, wrinkled skin | Maceration from excess moisture |
| Small bumps around individual hairs | Possible folliculitis |
| Spreading redness, increasing warmth, pus, odor, fever, or worsening pain | Possible infection requiring prompt assessment |
| Damage over a pressure point or beneath a medical device | Pressure, friction, shear, or device-related injury may also need consideration |
MARSI describes an association between the skin injury and a medical adhesive. Similar-looking damage can have another cause, and two conditions may occur together.
Who Is at Greater Risk of MARSI?
Anyone exposed to a medical adhesive can develop MARSI, but some people and situations require additional caution.
Skin and Patient-Related Risk Factors
- Infants and older adults
- Thin, dry, fragile, inflamed, or previously damaged skin
- A previous adhesive-related skin injury
- Eczema, dermatitis, or another skin disorder
- Edema or rapidly changing swelling
- Dehydration or poor nutritional status
- Diabetes or impaired circulation
- Critical or chronic illness
- Long-term corticosteroid use
- Treatments that affect skin integrity, such as some chemotherapy or radiation therapies
Adhesive and Care-Related Risk Factors
- Frequent adhesive application and removal
- Using stronger adhesion than the fixation task requires
- Repeatedly applying tape to the same location
- Rapid or high-angle removal
- Removing adhesive without supporting the skin
- Applying tape or a dressing border under tension
- Failing to inspect the skin during use
- Using products that are not compatible with skin preparations or one another
Environmental and Location-Related Risk Factors
- Heavy sweating
- Wound leakage
- Hot or humid conditions
- Placement across a joint
- Curved or difficult body contours
- Hair beneath the adhesive
- Swelling that develops during wear
- Long wear without appropriate reassessment
For a broader comparison of dressing options, see how to choose dressings and fixation for sensitive or easily damaged skin.
How Adhesive Application Can Damage the Skin
Even a relatively gentle medical adhesive can cause damage when it is applied incorrectly or used under unsuitable conditions.
Common application problems include:
- Stretching the tape. The tape may pull back against the skin after application.
- Stretching the dressing border. This can concentrate tension at the edges.
- Applying over wet skin. Moisture can weaken the skin and interfere with predictable adhesion.
- Applying over lotion or oily residue. This may affect fixation and lead to repeated repositioning.
- Creating wrinkles. Wrinkles can produce friction, uneven tension, and pressure.
- Using an unsuitable size. A product that is too small may pull at the wound or require excessive extra tape.
- Applying over irritated skin. Repeated adhesion may worsen existing barrier damage.
- Using unnecessary tape layers. More adhesive surface does not automatically mean safer fixation.
- Ignoring joint movement. An adhesive placed across a moving area may repeatedly pull on the skin.
- Repeatedly lifting and repositioning. Each removal exposes the skin to additional mechanical stress.
How to Help Prevent Medical Adhesive-Related Skin Injury
MARSI prevention should begin before the adhesive package is opened and continue until the product is fully removed.
Before Applying the Adhesive
- Inspect the skin for redness, moisture, dryness, peeling, rash, swelling, or previous damage.
- Ask about previous reactions to medical tape, dressings, electrodes, or adhesive devices.
- Identify whether the skin is fragile, swollen, moist, or likely to move significantly.
- Select the least aggressive adhesive that can safely perform the required fixation task.
- Check that the product is suitable for the location, expected wear conditions, and fixation requirement.
- Clean the skin according to the product or care instructions.
- Allow the skin to dry before application.
- Allow a compatible skin-barrier product to dry completely when one is used.
- Avoid placing ordinary fixation tape directly over damaged or open skin.
During Application
- Position the body part naturally before applying the product.
- Lay the tape or adhesive border onto the skin without unnecessary stretch.
- Smooth it gently to create even contact.
- Avoid wrinkles, gaps, and excessive overlapping.
- Do not repeatedly lift and reapply the same piece of adhesive.
- Use only the amount of tape needed for safe fixation.
- Do not place excessive tension around a limb or swollen area.
- Follow the specific manufacturer’s application instructions.
During Wear
- Monitor accessible edges and nearby skin.
- Watch for burning, itching, blistering, peeling, leakage, or increasing tension.
- Reassess the adhesive if swelling develops.
- Address leakage or sweat rather than covering the problem with more tape.
- Change the product when required by its instructions or the care plan.
- Avoid unnecessary dressing changes.
During Removal
- Loosen one edge carefully.
- Keep the adhesive close to the skin.
- Pull it back over itself rather than upward.
- Remove it slowly.
- Support the exposed skin at the peel line.
- Follow the direction of hair growth when practical.
- Pause if the skin starts lifting with the adhesive.
- Consider a compatible medical adhesive remover when appropriate.
How to Remove Medical Tape Without Damaging the Skin
The technique often described as “low and slow” is intended to reduce upward pulling on the epidermis.
Step 1: Inspect the Area
Before removal, check for:
- Blistering
- Visible skin lifting
- Bleeding
- Severe pain
- Moist, white, or broken skin
- Swelling beneath the adhesive
Extra caution or professional assistance may be needed when these findings are present.
Step 2: Release One Edge
Gently lift or roll one edge. Avoid scratching the skin with a fingernail or using an object that could cut the skin.
Step 3: Support the Skin
Use one hand to stabilize the skin beside the peel line. Continue moving the supporting fingers as more skin is exposed.
Step 4: Pull Low and Slow
Fold the adhesive back over itself so it remains close and approximately parallel to the skin. Remove it slowly rather than pulling vertically upward.
Step 5: Follow Hair Growth When Practical
Removing in the direction of hair growth may reduce pulling on hair follicles and discomfort.
Step 6: Stop if the Skin Begins to Lift
Do not continue applying force when the epidermis follows the tape. Pause and reassess the safest removal method.
Step 7: Consider an Adhesive Remover
A compatible medical-grade adhesive remover may help loosen strongly adhered products and reduce the force required for removal.
Use the remover according to its own instructions and confirm compatibility with the adhesive, dressing, device, and skin-barrier product. Do not place an adhesive remover into an open wound unless it is specifically intended for that use.
Step 8: Reassess the Skin
After removal, check for persistent redness, peeling, pain, blisters, rash, moisture damage, bleeding, or open skin.
Solventum’s medical adhesive application and removal guidance describes supporting the skin and removing tape low and slow by pulling it back over itself rather than perpendicular to the skin.
What Should You Do if Medical Adhesive Damages the Skin?
The appropriate response depends on whether the injury is skin stripping, a tear, blistering, dermatitis, maceration, folliculitis, or another condition.
General steps include:
- Stop and assess the product. Determine where the reaction occurred and whether the product is still needed for an essential dressing or medical device.
- Do not repeatedly apply adhesive over the injured area. Additional removal may worsen the damage.
- Assess whether the skin is intact. Look for peeling, open skin, a flap, blistering, moisture damage, rash, or bleeding.
- Clean the area according to the care plan. Avoid harsh rubbing or unapproved substances.
- Protect broken skin appropriately. A qualified professional may recommend a non-adherent or lower-trauma dressing based on the injury.
- Choose a different fixation approach when possible. This may include a different adhesive, a smaller adhesive footprint, netting, or tubular retention when appropriate.
- Address contributing factors. Manage leakage, sweating, friction, swelling, or repeated dressing changes.
- Record the suspected product and reaction. This may help prevent repeated exposure.
- Seek professional advice for significant or recurring injury.
Do not remove or weaken fixation for a critical medical device without appropriate instructions. Protecting the skin is important, but essential tubes, catheters, and devices must also remain safely secured.
There is no single ointment that is appropriate for every adhesive-related injury. Antibiotic ointments, corticosteroids, moisturizers, and protective dressings have different roles and should not be applied automatically without identifying the likely problem.
How to Choose a Medical Adhesive for At-Risk Skin
| Question | Why it matters |
|---|---|
| How much fixation is actually required? | Stronger adhesion is not automatically better for a light dressing or short-term task |
| How often will the adhesive be removed? | Frequent changes repeatedly expose the skin to mechanical stress |
| Is the skin fragile or previously injured? | A gentler adhesive or non-adhesive retention method may be considered |
| Is moisture expected? | Sweat and drainage can weaken skin and alter adhesion |
| Is the area curved or highly mobile? | Poor conformity may lead to tension, friction, or edge lifting |
| Is swelling likely? | A fixed adhesive may create tension as the tissue expands |
| Is the product securing a critical device? | Device safety and fixation strength must remain a priority |
| Could netting or tubular retention be used? | A compatible non-adhesive method may reduce direct adhesive exposure |
| Is a skin-barrier product being used? | Compatibility and drying time may affect adhesion and removal |
For gauze and lightweight dressing fixation, review how to compare medical tapes by skin condition, fixation needs, and expected water exposure.
Can Silicone Medical Tape Help Reduce Skin Trauma?
Soft silicone medical tapes are designed to adhere to intact skin while releasing with less aggressive removal force than some traditional high-tack adhesives.
They may be considered when:
- Gentle dressing fixation is needed
- The adhesive must be removed frequently
- The skin is fragile or sensitive
- Reducing removal trauma is a priority
- A lightweight, non-critical item needs securement
However, silicone tape cannot eliminate every risk of MARSI.
Silicone adhesive can still cause problems when:
- It is unsuitable for the fixation task
- It is stretched during application
- The skin is wet or already damaged
- Moisture or swelling develops beneath it
- It is repeatedly removed and reapplied
- It remains in place despite itching, blistering, or skin lifting
- It is removed incorrectly
The term “hypoallergenic” also does not mean allergy-proof or completely risk-free.
Learn how soft silicone medical tape adheres to and releases from intact skin.
Choosing a Gentler FRESINIDER Dressing and Fixation System
FRESINIDER offers several products that may perform different roles in a dressing and fixation system. Product selection should be based on the wound, surrounding skin, required absorption, fixation needs, and current instructions.
FRESINIDER Silicone Medical Tape
FRESINIDER Silicone Medical Tape uses a soft silicone adhesive and is intended for gentle, lightweight dressing fixation.
When using it:
- Apply it to clean, dry, intact skin
- Use only the amount required
- Avoid stretching it during application
- Monitor the skin for redness, itching, blistering, or lifting
- Remove it low and slow while supporting the skin
It should not be described as MARSI-proof, allergy-proof, or suitable for every medical device.
FRESINIDER Silicone Foam Dressing With Adhesive Border
FRESINIDER Silicone Foam Dressing with Adhesive Border combines an absorbent multilayer foam with an integrated soft silicone adhesive border.
An integrated border may reduce the need for separate strips of fixation tape. This can simplify the dressing system and reduce additional adhesive contact when the product is appropriate for the wound and surrounding skin.
However, it remains an adhesive dressing. The surrounding skin should be assessed before application, during wear, and after removal.
FRESINIDER Silicone Wound Contact Layer
FRESINIDER Silicone Wound Contact Layer provides a soft wound-contact interface and allows drainage to pass into an absorbent secondary dressing.
Because it requires secondary absorption and fixation, a compatible non-adhesive retention method may sometimes be considered when reducing adhesive exposure is important. The complete system must still remain securely positioned.
FRESINIDER Dressing Retention Tape
FRESINIDER Dressing Retention Tape is designed to secure compatible dressings and gauze over a broader area.
Because a larger surface area contacts the skin, it is not automatically the best choice for skin that is already stripped, blistered, or severely irritated. Apply it without tension and do not use extra tape merely to cover a saturated or leaking dressing.
Product selection principle: Choose the least aggressive adhesive that can safely perform the required task. Too little fixation can also be unsafe when an important dressing or medical device must remain secure.
Frequently Asked Questions
What Does MARSI Look Like?
MARSI may appear as persistent redness, shiny or peeled skin, a skin tear, blistering, an itchy or burning rash, white softened skin, or inflamed bumps around hair follicles. The appearance depends on whether the cause is mechanical damage, dermatitis, moisture, or follicular irritation.
Is MARSI the Same as a Medical Adhesive Allergy?
No. Allergic contact dermatitis is one possible form of MARSI, but many cases are caused by mechanical stripping, tension, moisture, irritation, repeated removal, or fragile skin rather than a true allergy.
How Long Should Redness Last After Removing Medical Tape?
A brief mark may result from pressure and does not automatically indicate injury. A commonly used MARSI definition includes redness or another abnormality that remains for about 30 minutes or longer. Persistent redness, pain, peeling, blistering, or open skin requires closer assessment.
Why Did Medical Tape Peel Off My Skin?
Possible reasons include fragile skin, stronger adhesion than necessary, repeated tape use, moisture, rapid removal, pulling upward instead of back over the tape, or failing to support the skin during removal.
Can Medical Tape Cause Blisters?
Yes. Tape or an adhesive border applied under tension may create a tension blister. Joint movement, friction, and swelling beneath a firmly fixed adhesive may also contribute.
Does Silicone Medical Tape Prevent MARSI?
No adhesive can guarantee prevention. Soft silicone tape may be considered when gentle fixation and lower-trauma removal are priorities, but skin assessment, application technique, moisture control, monitoring, and removal method remain important.
How Should Medical Tape Be Removed?
Support the skin at the peel line and remove the tape slowly at a low angle, folding it back over itself. Avoid pulling it vertically away from the skin. Stop if the skin begins lifting with the adhesive.
Can Tape Be Applied Over Skin Already Damaged by Adhesive?
Repeatedly applying adhesive over stripped, blistered, or torn skin may worsen the damage. A different fixation approach may be needed unless the product is specifically intended for that use and forms part of a professional care plan.
What Should Be Put on Skin Damaged by Medical Tape?
There is no single treatment for every case. Skin stripping, a skin tear, dermatitis, maceration, folliculitis, and infection require different approaches. Protect the area from further adhesive trauma and seek guidance when the injury is open, painful, extensive, recurrent, or difficult to identify.
Can a Skin-Barrier Product Prevent MARSI?
A compatible barrier product may help protect at-risk skin in some situations, but it must be selected and applied according to its instructions. It should be allowed to dry fully, and compatibility with the adhesive must be confirmed.
When to Contact a Healthcare Professional
Seek professional assessment when:
- A large area of skin has peeled away
- A skin flap or significant skin tear is present
- There is bleeding that does not stop with gentle pressure
- A large, painful, or tense blister develops
- The rash is severe, spreading, or repeatedly returns
- The skin is increasingly painful, warm, swollen, or red
- Pus, unusual drainage, or a foul odor appears
- Fever, chills, or general illness develops
- The adhesive is securing an important medical device
- The injured person has diabetes, impaired circulation, fragile skin, or a weakened immune system
- You cannot determine whether the problem is MARSI, infection, pressure injury, or another condition
Emergency care is appropriate for difficulty breathing, facial or throat swelling, faintness, or another sign of a severe allergic reaction.
Final Thoughts
Medical adhesive-related skin injury is not limited to an allergy to tape. It can include mechanical skin stripping, tension blisters, skin tears, irritant or allergic dermatitis, maceration, and folliculitis.
The risk depends on more than the adhesive material. Skin condition, fixation strength, moisture, swelling, body location, application tension, repeated dressing changes, and removal technique all affect how the skin responds.
Important prevention principles include:
- Assess the skin before applying an adhesive
- Choose the least aggressive adhesive that can safely perform the task
- Apply to clean, dry skin when appropriate
- Avoid unnecessary tension and wrinkles
- Monitor for moisture, swelling, itching, burning, and blistering
- Avoid unnecessary adhesive changes
- Support the skin during removal
- Remove tape low and slow by folding it back over itself
- Do not repeatedly tape over injured skin
- Seek professional help for significant, recurrent, or uncertain reactions
Soft silicone tape and silicone-bordered dressings may be useful options when gentler fixation is a priority, but no adhesive is completely risk-free. The safest approach combines appropriate product selection with careful application, regular skin assessment, moisture control, and lower-trauma removal.
About the Author
FRESINIDER Editorial Team
The FRESINIDER Editorial Team creates educational content about wound dressings, medical tapes, bandages, skin protection, and everyday wound care. Our articles are developed using reputable clinical guidance, relevant medical sources, and current product information to help readers better understand general wound-care options.
Medical Disclaimer
This article is intended for general educational purposes only and does not constitute medical advice, diagnosis, or treatment. Skin reactions associated with medical adhesives may have different causes and require different management. Do not remove or weaken the fixation of a critical medical device without appropriate professional instructions. Consult a qualified healthcare professional for significant skin loss, blistering, persistent dermatitis, suspected infection, allergic symptoms, chronic wounds, surgical wounds, diabetic wounds, or reactions that are recurrent, worsening, or difficult to identify.
