In the "H" category, the principal objective and purpose to be served by this classification and its application is to establish areas permitting horticultural uses and by means of the standards and requirements set forth herein, to maintain a desirable environment within the areas designated for such uses.

In the "R" category, that classification which establishes the lowest population density and requires the highest standards of lot area, yards and open spaces is considered to be the most restrictive, and the uses permitted in such classification are considered to be the lightest and most restrictive. The R-1 classification and the uses permitted therein on lots containing less than eight thousand square feet are considered to be the lightest and most restrictive. In this classification a further distinction is made in terms of required minimum lot area per dwelling unit. The degree of restrictiveness in such matters increases as lot size increase to, but not including eight thousand square feet. On lots containing eight thousand square feet or more, the lot area per dwelling unit decreases. As greater population density is permitted by classification, the uses permitted are considered to be heavier and less restrictive in the following sequence—R-2, R-1 lots containing eight thousand square feet or more, R-3 and R-4.

In the "C" category, that classification which establishes the most stringent performance standards is considered to be the most restrictive commercial classification, and the uses permitted in such classification are considered to be the most restrictive commercial uses. In the commercial category as set forth in this title, the Regional Commercial classification and the uses permitted therein are the most restrictive, and the classifications and uses become less restrictive in the following sequence—C-2, CM and C-3.

In the "M" category, that classification which establishes the most stringent performance standards is considered to be the lightest and most restrictive industrial classification and the uses permitted in such classification are considered to be the lightest and most restrictive. In the industrial category as set forth in this title, M-1 classification and the uses permitted therein are the lightest and most restrictive, and the classifications and uses become heavier and less restrictive in the M-2 classification.

Where such boundaries are indicated as approximately following street or alley lines or lot lines, such lines shall be construed to be such boundaries;

In the case of unsubdivided property, and where a zone boundary divides such property, the location of such boundaries, unless the same are indicated by dimensions, shall be determined by use of the scale appearing on said zoning map;

Where a lot or lots subdivided and recorded subsequent to the zoning of the area in which they are located become so placed that they are unequally bisected longitudinally by the boundary lines of different zones, the zone boundary may be considered as following the lot lines of the lot or lots so bisected in such manner as to place a lot wholly in that zone classification which applied to the major portion of the lot before the zone boundary was adjusted;

Where a lot or lots are equally bisected longitudinally by a zone boundary line, the total lot shall acquire the most restrictive use classification of the two zone classifications involved;

Where a lot or lots are bisected by the boundary line between two zones and such boundary line parallels or approximately parallels the street on which such bisected lot or lots shall acquire the classification of that zone within which the front portion of the bisected lot or lots lie. This provision shall not apply to through lots;

Where a public street or alley is officially vacated or abandoned, the area comprising such vacated street or alley shall acquire the classification of the property to which it reverts;

Areas of dedicated streets or alleys and railroad rights-of-way other than such as are designated on the zoning map as being classified in one of the zones provided in this title, shall be deemed to be unclassified and, in the case of streets, permitted to be used only for street purposes as defined by law, and, in the case of railroad rights-of-way, permitted to be used solely for the purpose of accommodating tracks, signals, other operative devices and the movement of rolling stock.

If a prezoning map for an area has been adopted, then such annexing property contained therein shall, upon becoming a part of the city, possess the classification indicated on the detailed prezoning map, and such portions of the detailed prezoning map governing properties so annexed shall become a part of the city's zoning map and thereafter be subject to all of the provisions of this title.

If a prezoning map for an area has not been adopted, then such area shall, upon annexation, be deemed to be temporarily zoned as R-1 under this title until said land is classified after being processed as an amendment to the zoning map. However, the council may, upon the recommendation of the planning commission, invoke a classification on such annexing properties other than R-1 by the adoption of an emergency interim ordinance when deemed necessary for the protection of the health, safety and welfare of the city and the property involved. Formal proceedings, however, must be instituted within one year from the effective date of the interim ordinance to properly amend the zoning ordinance in the manner set forth in Chapter 17.62, and the interim ordinance repealed.

Any known and identifiable use which has been omitted from the list of permitted uses in any classification, or uses which have newly come into existence by reason of new technological developments in the trades, sciences and equipment;

Any use already listed in a classification but which, because of new processes, equipment or materials used possesses measurably different performance standards than do the other uses in that classification and which may warrant subject use being made permissible in a more restrictive classification.

For purposes of arriving at determinations under this title, the degree of compatibility of any use within either of these two circumstances to other uses shall be evaluated. So far as technical evidence and scientific means of measurement are available they shall be considered in determining the form and intensity of performance standards typically associated with any identifiable type of use. The term "performance standards" as here employed refers to such conditions or effects which result from the maintenance and operation of any principal use including, but not limited to the flow of sound measured in decibels; ambient level of sound; vibrations above and below the auditory range; odors, fumes, smoke or other emissions whether toxic or nontoxic; incidence of hazard, odors, fumes, smoke or other emissions whether toxic or nontoxic; incidence of hazard, including explosion or contamination; the identification and classification in terms of chemical composition of the emissions from any type of use whether industrial, commercial or domestic; the traffic-generating capacity, both in terms of freight and passengers, the volume of either or both, and the time or times of daily cycle that represent peak flow or minimum flow; the consuming capacity of and need for electrical energy, natural gas, oil, water, sewage disposal and transportation facilities including water, rail and air.

In no case, however, shall a use determined in this manner to be a commercial use be permitted to locate in a residential zone, nor shall any use determined to be an industrial use be permitted to locate in a strictly commercial zone.

The city may initiate proceedings under this title, or any person may file a written application for such determination with the planning commission upon forms supplied by the city, and such application shall be accompanied by such data as is available to the applicant on the factors enumerated herein as they apply to the subject use.

An up-to-date list of all uses classified pursuant to this title shall be maintained in the office of the building department and, at least once each year, copies of such list shall be prepared and made available to all persons requesting same.