B

Report Recommendations

Recommendation: Groups undertaking studies and considering new regulations under Agenda Item 1.1, related to protection of the 50.2–50.4 GHz frequency band from transmissions in the adjacent 47.2–50.2 GHz and 50.4–51.4 GHz (Earth-to-space) bands, should

• Consider realistic environmental conditions, similar to current operational use—for example, by varying latitude, surface type, and weather conditions.
• Assess the potential for out-of-band emissions (OOBE) as a function of orbital observing configurations—for example, polar and equatorial orbits, cross-track and conical scanning techniques, microwave imagers and sounders, varying Earth incidence angles and instantaneous field of view, low Earth orbit, and potentially geostationary orbit (GSO).
• Ensure that the OOBE limits and/or provision of additional guard bands are sufficient to meet Recommendation ITU-R RS.2017-0 limits as a function of sensor bandwidth and polarization.
• Ensure aggregate OOBE from aeronautical Earth stations in motion (A-ESIMs) into the critical RR 5.340 band from 48.94–49.04 GHz do not exceed levels set in RR 5.555B.

• Take into account, in all sharing and compatibility studies, the impact of future aggregate interference and OOBE, including emission from harmonics, that exceed the Recommendation ITU-R RA.769-2 interference thresholds. (Agenda Item 1.1)

Recommendation: Administrations should use local coordination—for example, through radio quiet zones—to protect radio astronomy observatories, taking into account not only terrestrial emitters but also spaceborne emitters. (Agenda Items 1.1, 1.7, and 1.11, Preliminary Agenda Items 2.9 and 2.14)

Recommendation: Groups undertaking studies on the technical and operational limitations regarding the minimum antenna size and associated power limitations under Agenda Item 1.2 should include consideration of out-of-band emissions that could affect the current Earth exploration-satellite service (active) use in the adjacent band from 13.25–13.75 GHz. The methodology and thresholds detailed in Recommendation ITU-R RS.1166-5 should also be applied when devising restrictions on transmissions from Earth stations in the fixed-satellite service. (Agenda Item 1.2)

Recommendation: For Earth remote sensing observations, groups undertaking studies of the 50.2–50.4 GHz and 52.6–54.25 GHz oxygen absorption bands under Agenda Item 1.3 should

• Assess the necessary out-of-band emission (OOBE) limits for uplink transmissions that satisfy Recommendation ITU-R RS.2017-0 criteria for sensors with characteristics described in Recommendation ITU-R RS.1861-1.
• Consider realistic environmental conditions, similar to current operational use—for example, by varying by latitude, surface type, and weather conditions.
• Assess the potential for OOBE as a function of orbital observing configurations—for example, polar and equatorial orbits, cross-track and conical scanning techniques, microwave imagers and sounders, varying Earth incidence angles and instantaneous field of view, low Earth orbit, and potentially geostationary orbit (GSO).

• Assess whether current Resolution 750 (Rev. WRC-19) limits provide adequate protection from aggregated GSO and non-GSO emissions. (Agenda Item 1.3)

Recommendation: Groups undertaking studies of new allocations and associated equivalent power flux-density limits under Agenda Item 1.4 should include consideration of the potential for of out-of-band emissions that could affect the current Earth exploration-satellite service (active) use in the adjacent band. The thresholds for interference defined in ITU-R RS.1166-5 should be the starting point for such considerations. (Agenda Item 1.4)

Recommendation: Those undertaking studies of increased equitable access to specific bands under Agenda Item 1.6 should consider the potential implications for radio astronomy facilities hosted in lightly populated radio-quiet (and thus potentially underserved) areas. (Agenda Item 1.6)

Recommendation: In considering new mobile use of the 4.4–4.8 GHz band in response to Agenda Item 1.7, administrations should take all practicable steps (e.g., radio quiet zones and/or other coordination approaches) to protect the radio astronomy service in the adjacent 4.8–5.0 GHz band, and Earth exploration-satellite service (passive) in the 4.2–4.4 GHz band for which a new primary allocation is considered under WRC-27 Agenda Item 1.19. (Agenda Item 1.7)

Recommendation: Groups undertaking studies of new or revised allocations to the 14.8–15.35 GHz band under Agenda Item 1.7 should

• Explicitly consider the impact to the radio astronomy service (RAS) and Earth exploration-satellite service (EESS, passive) to which the 15.35–15.4 GHz band is allocated on a primary basis.
• Specify out-of-band emission (OOBE) masks and/or guard bands to ensure that the Recommendation ITU-R RA.769-2 and Recommendation ITU-R RS.2017-0 interference thresholds, for RAS and EESS (passive), respectively, are not exceeded in these bands. Special consideration should also be given to keeping aggregate interference below this threshold.

• Take into account in all sharing and compatibility studies the impact of future aggregate interference and OOBE, including emission from harmonics that exceeds the ITU-R RA.769-2 interference thresholds. (Agenda Item 1.7)

Recommendation: Groups undertaking studies related to Agenda Item 1.7 should examine the potential for International Mobile Telecommunications usage in the lower portion of the 7125–8400 MHz band to interfere with Earth exploration-satellite service (passive) observations made over oceans. If necessary, administrations should restrict usage of all or part of this band to inland regions. (Agenda Item 1.7)

Recommendation: Groups undertaking studies and considering new allocations under Agenda Item 1.8 in the bands from 231.5–700 GHz should

• Limit allocations to the radiolocation service (RLS) in bands from 231.5–275 GHz to ground-based or maritime use only, with no airborne or spaceborne transmissions permitted. Similarly, identifications for RLS transmission in 275–700 GHz should be limited to ground-based or maritime usage only.
• Identify criteria needed to ensure that RLS transmissions do not result in exceedance of the thresholds given in Recommendation ITU-R RS.2017-0 for any Earth exploration-satellite service (EESS, passive) bands in the frequency ranges under consideration in this agenda item.
• Consider impacts of aggregate emissions.
• Consider impacts of reflections off land surfaces, structures, vehicles, and clouds, any of which can redirect nominally horizontally oriented transmissions skyward toward an orbiting EESS (passive) sensor.
• Identify criteria, such as separation distance, needed to ensure that outdoor applications, such as vehicle sensors and personal devices, do not exceed the thresholds given in Recommendation ITU-R RA.769-2, adopting the continuum spectral power flux-density limits at 270 GHz for use at higher frequencies. (Agenda Item 1.8)

Recommendation: Noting the importance of radio quiet zones and other steps taken to protect radio astronomy service observations, administrations should require future applications of radiolocation service technology to be engineered with the capability for the user to disable transmissions when necessary. (Agenda Item 1.8)

Recommendation: Groups performing studies under Agenda Item 1.9 should bear in mind potential interference into radio astronomy observations in the 13.36–13.41 MHz band. (Agenda Item 1.9)

Recommendation: Groups undertaking studies under Agenda Item 1.9 should examine potential compatibility issues between anticipated new services and the ionosonde-based active remote sensing technique.

Recommendation: Groups studying modifications to spaceborne services under Agenda Item 1.10 should

• Ensure that out-of-band emission (OOBE) masks for the 71–76 GHz space-to-Earth band are sufficient to protect radio astronomy observations in the adjacent 76–77.5 GHz band, which is allocated to the radio astronomy service (RAS) on a primary basis, to within the detrimental interference thresholds identified in Recommendation ITU-R RA.769-2.
• Ensure that power flux-density and equivalent isotropic radiation power limits, and OOBE masks for the 81–86 GHz Earth-to-space band are sufficient to protect passive observations in the 86–92 GHz band allocated to RAS and Earth exploration-satellite service (EESS, passive) on a primary basis, and subject to RR 5.340. Masks should be sufficient to ensure that interference into RAS and EESS (passive) observations remains below the detrimental interference thresholds identified in Recommendations ITU-R RA.769-2 and ITU-R RS.2017-0 for RAS and EESS (passive), respectively.
• Ensure that the cited thresholds are met including in the case of aggregate emissions from realistic levels of deployment of orbiting and ground-based transmitters.
• Ensure that actions taken are consistent with those taken under WRC-27 Agenda Item 1.18, which consid

• ers protection of RAS and EESS (passive) observations in a range of bands above 76 GHz, including those noted above. (Agenda Item 1.10)

Recommendation: Administrations should ensure that the aggregate sidelobe emissions from ground stations transmitting in the Earth-to-space direction in the 81–86 GHz band, which is shared with the radio astronomy service (RAS) and covered by RR 5.149, do not exceed the thresholds identified in Recommendation ITU-R RA.769-2 at any RAS observatory site. (Agenda Item 1.10)

Recommendation: Administrations should note the critical importance of the opportunistic use of the 71–76 GHz band, together with the contiguous primary and secondary allocations to the radio astronomy service above 76 GHz, for deep cosmological surveys carried out from specific remote locations. They are urged to facilitate coordination of such observations with active uses of the bands. (Agenda Item 1.10)

Recommendation: Groups conducting studies of new or revised allocations in the 1610–1645.5 MHz, 1646.5–1660 MHz, and 1670–1675 MHz bands under Agenda Item 1.11 should

• Explicitly consider the impact to radio astronomy observations conducted the bands 1610.6–1613.8 MHz, which is allocated to the radio astronomy service (RAS) on a primary basis and the 1660–1670 MHz band, parts of which are allocated to RAS.
• Design thresholds for OOBE and spurious emissions to ensure that the Recommendation ITU-R RA.769-2 interference thresholds, −251 dB(W/(m² Hz)) for continuum observations, and −237 dB(W/(m² Hz)) for spectral line observations are not exceeded in these RAS bands.
• Consider the impacts of both out-of-band emissions and aggregate interference. (Agenda Item 1.11)

Recommendation: Groups undertaking studies of new space-to-Earth and Earth-to-space mobile-satellite service transmissions in the 1427–1432 MHz band under Agenda Item 1.12 should ensure that

• Requirements for out-of-band emission (OOBE) masks are sufficient to ensure that the interference thresholds given in Recommendation ITU-R RA.769-2 and Recommendation ITU-R RS.2017-0, for the radio astronomy service and the Earth exploration-satellite service (EESS, passive), respectively, are not exceeded, including for the case where Earth-to-space transmissions fall within the portion of cold-space used by EESS (passive) sensors for radiometric calibration.
• These studies include consideration of aggregate emissions from multiple transmitters and consider incorporating information on interference from OOBE observed by the Soil Moisture Active Passive and Soil Moisture Ocean Salinity missions.
• Any revisions to the Radio Regulation urge administrations to ensure that the above thresholds are not exceeded in aggregate, through limitations of the number of licenses granted or by other regulatory mechanisms.
• The potential for permanent damage to EESS (passive) sensors from nearby active transmitters is assessed and any needed mitigation identified. (Agenda Item 1.12)

Recommendation: Groups undertaking compatibility studies under Agenda Item 1.13 should evaluate the ability of active beam synthesis to be leveraged to ensure continuous avoidance and nulling of transmissions toward specific locations, including, but not limited to, radio astronomy service facilities within radio quiet zones and beyond. Such studies should also follow the methodology outlined in Recommendation ITU-R RA.769-2 when identifying thresholds for the degree of antenna gain minimization in the direction of the avoidance location, as well as for out-of-band emissions and spurious emissions. (Agenda Item 1.13)

Recommendation: Administrations should require coordination agreements between spaceborne International Mobile Telecommunications (IMT) operators and radio astronomy service (RAS) facilities. In addition to formalizing arrangements for steering of beam nulls, discussed above, these agreements should include (potentially time-dependent) coordination of spectral occupancy, aimed at providing an agreed minimum

level of IMT network access in the neighborhood of key RAS facilities while retaining as much scientific capability as feasible. (Agenda Item 1.13)

Recommendation: Groups considering new allocations under Agenda Item 1.13 should

• Not adopt new allocations to the mobile-satellite service (MSS) in the 1427–1518 MHz International Mobile Telecommunications band identified in Recommendation ITU-R M.1036-7, given the adjacency to the 1400–1427 MHz band that is a cornerstone for both radio astronomy and Earth remote sensing observations, and that is afforded RR 5.340 “all emissions prohibited” protection.
• Not adopt new allocations to MSS in the 2640–2700 GHz bands allocated to the radio astronomy service and/or Earth exploration-satellite service (passive). (Agenda Item 1.13)

Recommendation: In regard to Agenda Item 1.15, administrations should develop lunar communications systems with sufficient redundancy to be able to retune to avoid specific bands should those bands prove to contain phenomena of interest to radio astronomy. (Agenda Item 1.15)

Recommendation: Wherever practicable, administrations should preferentially use optical wavelengths for communications to, from, and within the lunar environment. (Agenda Item 1.15)

Recommendation: Groups undertaking studies of communications in the lunar environment under Agenda Item 1.15 should

• Pay particular attention to the potential for interference into the 2690–2700 MHz radio astronomy band to permit comparisons with terrestrial observations made in this band.
• Follow the methodology described in Recommendation ITU-R RA.769-2 when quantifying harmful levels of interference into radio astronomy observations in the lunar environment. The thresholds that result from this methodology may be more restrictive than those for terrestrial radio astronomy due to the wider bandwidths, longer integration times, and the differences

• in the operating environment that are possible in the shielded zone of the Moon.
• Take into account the protections afforded to the radio astronomy service (RAS) in Section V of Article 22 of the Radio Regulations.
• Focus in particular on impacts of out-of-band emissions and spurious emissions on RAS observations. (Agenda Item 1.15)

Recommendation: Groups considering appropriate technical and/or regulatory measures based on the results of studies undertaken under Agenda Item 1.16 should consider coordination agreements with satellite network operators as a mechanism to protect radio astronomy operating within the radio quiet zones. (Agenda Item 1.16)

Recommendation: Groups undertaking studies under Agenda Item 1.16 should take into account both single and aggregate interference from non-geostationary orbit transmissions when computing detrimental interference into radio astronomy bands. (Agenda Item 1.16)

Recommendation: Groups considering appropriate technical and/or regulatory measures based on the results of studies undertaken under Agenda Item 1.16 should consider mechanisms that allow additional key radio astronomy service facilities (such as those listed in Table 2-5) to be afforded protections comparable to those that may be established for the Square Kilometre Array Observatory and/or the Atacama Large Millimeter/submillimeter Array as a result of 2027 World Radiocommunication Conference actions. (Agenda Item 1.16)

Recommendation: Groups undertaking studies of non-geostationary orbit interference into RAS facilities in radio quiet zones under Resolution 681 (WRC-23) “resolves to invite…” items 3 through 6 should consider continued protection for radio astronomy service observations across all bands, including those below 10 GHz, not just those identified under “resolves to invite...” items 1 and 2. (Agenda Item 1.16)

Recommendation: In conjunction with and building upon the work under Agenda Item 1.17, the responsible International Telecommunication Union Radiocommunication Sector Study

group(s) should continuously update the frequencies listed in Report ITU-R RS.2456-1 as appropriate

Recommendation: Groups undertaking studies under Agenda Item 1.17 should examine the radio frequency needs of future receive-only space weather observing networks that will use distributed sensor architectures. (Agenda Item 1.17)

Recommendation: Groups undertaking studies under Agenda Item 1.18 should establish masks for out-of-band emissions and spurious emissions such that unwanted emission thresholds using the methodology in ITU-R SM.2091-0 are met at radio astronomy service (RAS) observatories in adjacent RAS primary and RR 5.340 bands. (Agenda Item 1.18)

Recommendation: Given that portions of the 123–130 GHz and 167–174.5 GHz active bands are also covered by RR 5.149, administrations should undertake all practicable steps to implement spatiotemporal coordination that achieves interference levels consistent with ITU-R RA.769-2 during radio astronomy service observations. (Agenda Item 1.18)

Recommendation: Groups undertaking studies under Agenda Item 1.18 should identify masks for out-of-band emissions and spurious emission such that the Earth exploration-satellite service (EESS, passive) interference thresholds given in ITU-R RS.2017-0 are not exceeded. The derivation of these masks should consider

• Impact of aggregate interference based on realistic expectations of the number of transmitters (ground based and spaceborne).
• Potential for interference through reflections of spaceborne transmissions off Earth’s surface.
• Potential for interference through transmission into the cold-sky calibration beams of an EESS (passive) sensor. (Agenda Item 1.18)

Recommendation: Groups undertaking studies under Agenda Item 1.18 should examine the potential for permanent damage to Earth exploration-satellite service (passive) sensors from nearby active transmitters and any needed mitigation should be identified. (Agenda Item 1.18)

Recommendation: The International Telecommunication Union Radiocommunication Sector and administrations should rapidly enact the new proposed primary allocations to the Earth exploration-satellite service (passive) under consideration in Agenda Item 1.19. (Agenda Item 1.19)

Recommendation: Groups undertaking studies under the 2031 World Radiocommunication Conference Preliminary Agenda Items 2.1 and 2.6 should ensure that future deployment of International Mobile Telecommunications or other technologies in the bands under consideration in these two preliminary agenda items does not cause harmful interference to with radio astronomy service (RAS) or Earth exploration-satellite service (EESS, passive) observations. Specifically, the studies should

• Use the thresholds given in Recommendations ITU-R RA.769-2 and ITU-R RS.2017-0 for RAS and EESS (passive), respectively, as the starting point for any consideration of interference. In the case of the RAS (ITU-R RA.769-2) recommendations, the “continuum” thresholds should be applied.
• Consider aggregate interference from realistic levels of deployment of future services.
• Include studies of the extent to which signals in these bands, even when largely directed horizontally, can reflect off Earth’s surface and be directed into an EESS (passive) sensor’s field of view. (Preliminary Agenda Items 2.1 and 2.6)

Recommendation: Groups undertaking studies under Preliminary Agenda Item 2.2 for the 2031 World Radiocommunication Conference should ensure the continued protection of radio astronomy service (RAS) and Earth exploration-satellite service (EESS, passive) observations in bands allocated to those services that are adjacent to planned beamed wireless power transmission (WPT) transmissions. Specifically, studies should

• Quantify the limits on beamed WPT out-of-band emissions (OOBE) that will be needed to ensure that the interference thresholds identified in Recommendations ITU-R RA.769-2 and ITU-R RS.2017-0, for RAS and EESS (passive), respectively, are not exceeded.

• Include consideration of aggregate emissions from multiple uncoordinated WPT devices and systems in devising those OOBE limits. (Preliminary Agenda Item 2.2)

Recommendation: Groups undertaking studies under Preliminary Agenda Item 2.3 of the 2031 World Radiocommunication Conference should ensure protection of Earth exploration-satellite service (EESS, passive) observations in the 10.6–10.7 GHz band from unwanted out-of-band emissions (OOBE) from the adjacent 10.7–10.95 GHz (space-to-Earth) downlink band serving aeronautical Earth stations in motion (A-ESIMs) and maritime Earth stations in motion (M-ESIMs) operating in the 12.75–13.25 GHz (Earth-to-space) uplink band. Specifically, studies should

• Produce realistic estimates of transmission loss factors for direct and Earth-reflected power coupled from downlink transmissions into an EESS (passive) sensor, considering interference into both Earth-observing beams and observations of cold space used for calibration.
• Derive thresholds for unwanted OOBE into the 10.6–10.7 EESS (passive) band from 10.7–10.95 GHz downlink transmission links serving A-ESIMs and M-ESIMs, sufficient to satisfy the interference thresholds in Recommendation ITUR RS.20170, and taking into account realistic models for the aggregate number of simultaneously active links. (Preliminary Agenda Item 2.3)

Recommendation: The International Telecommunication Union Radiocommunication Sector should consider expanding the scope of this preliminary agenda item to study impacts on radio astronomy observations in the radio astronomy service primary allocation from 10.6–10.7 GHz. (Preliminary Agenda Item 2.3)

Recommendation: Groups undertaking studies and considering new regulatory provisions under Preliminary Agenda Item 2.4 of the 2031 World Radiocommunication Conference should

• Ensure, through implementation of guard bands or suitable out-of-band emission limits, that interference

• into Earth exploration-satellite service (EESS, passive) observation in the 6425–7250 MHz band, and those planned for 4200–4400 GHz, remain below the thresholds given in Recommendation ITU-R RS.2017-0.
• Consider realistic levels of aggregate emissions in devising the protection criteria detailed in the above bullet.
• Examine the potential for permanent damage to EESS (passive) sensors from nearby active transmitters and require suitable mitigation if warranted. (Preliminary Agenda Item 2.4)

Recommendation: Groups studying potential future use of the 5030–5250 MHz band by RNSS under Preliminary Agenda Item 2.9 of the 2031 World Radiocommunication Conference should include consideration of what out-of-band emission (OOBE) limits will be needed to ensure that

• Interference into the radio astronomy service (RAS) observations at 5000 MHz and lower frequencies falls below the thresholds given in Recommendation ITU-R RA.769-2.
• Interference into the Earth exploration-satellite service (EESS, active) observations in the immediately adjacent 5250–5570 MHz band falls below the thresholds given in Recommendation ITU-R RS.1166-5.
• The above-noted thresholds are not exceeded when aggregate transmissions from realistic numbers of transmitters impact an RAS or EESS (active) sensor. (Preliminary Agenda Item 2.9)

Recommendation: Groups undertaking studies of new Earth-to-space transmissions in the 22.55–23.15 GHz band under Preliminary Agenda Item 2.10 of the 2031 World Radiocommunication Conference should

• Ensure that out-of-band emission (OOBE) limits for new Earth-to-space transmissions are sufficient to keep interference into the 23.6–24.0 GHz band, allocated to the Earth exploration-satellite service (EESS, passive) and the radio astronomy service (RAS), below the thresholds given in Recommendations ITU-R RS.2017-0 and ITU-R RA.769-2, respectively.
• Consider the impact of aggregate emissions in ascertaining the OOBE limits described above.

• Identify the separation distances between EESS (Earth-to-space) ground stations and RAS facilities that would be sufficient to ensure protection of observations in the overlapping 22.81–22.86 GHz and 23.07–23.12 GHz bands within which, under RR 5.149, administrations are urged to take “all practicable steps” to protect RAS observations. (Preliminary Agenda Item 2.10)

Recommendation: Groups undertaking studies of new space-to-Earth usage of selected bands within 37.5–54.2 GHz and considering new/revised allocations under Preliminary Agenda Item 2.11 of the 2031 World Radiocommunication Conference should

• Refrain from recommending new space-to-Earth allocations in or directly adjacent to bands in this range having a primary allocation to the Earth exploration-satellite service (EESS, passive) or the radio astronomy service (RAS), or afforded “all practicable steps” protection under RR 5.149. The two bands listed under RR 5.340 (“all emissions prohibited”) in this range should be given particular consideration in this regard.
• Ensure that guard bands, out-of-band emission (OOBE) masks or other suitable measures are required to keep interference from new space-to-Earth transmissions into any bands allocated to RAS below the thresholds given in Recommendation ITU-R RA.769-2.
• Ensure that guard bands, OOBE masks or other suitable measures are required to keep interference from new space-to-Earth transmissions into any bands allocated to EESS (passive), through reflection of Earth’s surface, below the thresholds given in Recommendation ITU-R RS.2017-0. (Preliminary Agenda Item 2.11)

Recommendation: Administrations authorizing any over-land or near-land Earth exploration-satellite service (active) observations resulting from Preliminary Agenda Item 2.12 of the 2031 World Radiocommunication Conference should require operators to coordinate observations with radio astronomy service facility operators on a global basis. (Preliminary Agenda Item 2.12)

Recommendation: Groups undertaking studies under Preliminary Agenda Item 2.13 of the 2031 World Radiocommunication Conference, in addition to ascertaining the current extent of interference from the Earth exploration-satellite service (active) into operations under the radiodetermination services, should determine the minimum acceptable limits for transmit power levels and duty cycles of X-band synthetic aperture radar systems that avoid compromising the quality of products required by their applications. (Preliminary Agenda Item 2.13)

Recommendation: Groups undertaking studies under Preliminary Agenda Item 2.13 of the 2031 World Radiocommunication Conference should consider the potential for damage to radio astronomy service facilities from spaceborne synthetic aperture radar sensors, and urge administrations to require coordination accordingly. (Preliminary Agenda Item 2.13)

Recommendation: Groups responsible for developing final agenda items and associated resolutions for the 2031 World Radiocommunication Conference (WRC-31) should amend Resolution 722, and/or any successor resolution that defines a related finalized WRC-31 agenda item, to invite studies of the damage hazard and of suitable coordination mechanisms between the Earth exploration-satellite service (active) and the radio astronomy service. (Preliminary Agenda Items 2.12 and 2.13)

Recommendation: Those undertaking studies under Preliminary Agenda Item 2.14 of the 2031 World Radiocommunication Conference should

• Ensure the continued protection of the radio astronomy service observations when considering allocations in and adjacent to the 608–614 MHz band.
• Require out-of-band emission masks and/or guard bands to ensure that the Recommendation ITU-R RA.769-2 interference thresholds are not exceeded in the 608–614 MHz band, including consideration of aggregate interference from multiple transmitters. (Preliminary Agenda Item 2.14)